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Čuda J, Pyšková K, Hejda M, Foxcroft LC, MacFadyen S, Storch D, Tropek R, Zambatis G, Pyšek P. Habitat modifies the relationship between grass and herbivore species richness in a South African savanna. Ecol Evol 2024; 14:e11167. [PMID: 38623521 PMCID: PMC11016939 DOI: 10.1002/ece3.11167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 03/01/2024] [Accepted: 03/06/2024] [Indexed: 04/17/2024] Open
Abstract
The savanna ecosystem is dominated by grasses, which are a key food source for many species of grazing animals. This relationship creates a diverse mosaic of habitats and contributes to the high grass species richness of savannas. However, how grazing interacts with environmental conditions in determining grass species richness and abundance in savannas is still insufficiently understood. In the Kruger National Park, South Africa, we recorded grass species and estimated their covers in 60 plots 50 × 50 m in size, accounting for varying proximity to water and different bedrocks. To achieve this, we located plots (i) near perennial rivers, near seasonal rivers, and on crests that are distant from all water sources and (ii) on nutrient-rich basaltic and nutrient-poor granitic bedrock. The presence and abundance of large herbivores were recorded by 60 camera traps located in the same plots. Grass cover was higher at crests and seasonal rivers than at perennial rivers and on basalts than on granites. The relationship between grass species richness and herbivore abundance or species richness was positive at crests, while that between grass species richness and herbivore species richness was negative at seasonal rivers. We found no support for controlling the dominance of grasses by herbivores in crests, but herbivore-induced microsite heterogeneity may account for high grass species richness there. In contrast, the decrease in grass species richness with herbivore species richness at seasonal rivers indicates that the strong grazing pressure over-rides the resistance of some species to grazing and trampling. We suggest that the relationships between grasses and herbivores may work in both directions, but the relationship is habitat-dependent, so that in less productive environments, the effect of herbivores on vegetation prevails, while in more productive environments along rivers the effect of vegetation and water supply on herbivores is more important.
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Affiliation(s)
- Jan Čuda
- Department of Invasion EcologyCzech Academy of Sciences, Institute of BotanyPrůhoniceCzech Republic
| | - Klára Pyšková
- Department of Invasion EcologyCzech Academy of Sciences, Institute of BotanyPrůhoniceCzech Republic
- Department of Ecology, Faculty of ScienceCharles UniversityPragueCzech Republic
| | - Martin Hejda
- Department of Invasion EcologyCzech Academy of Sciences, Institute of BotanyPrůhoniceCzech Republic
| | | | - Sandra MacFadyen
- Centre for Invasion Biology, Department of Botany and ZoologyStellenbosch UniversityMatielandSouth Africa
- Department of Mathematical SciencesStellenbosch UniversityMatielandSouth Africa
| | - David Storch
- Department of Ecology, Faculty of ScienceCharles UniversityPragueCzech Republic
- Centre for Theoretical StudiesCharles UniversityPragueCzech Republic
| | - Robert Tropek
- Department of Ecology, Faculty of ScienceCharles UniversityPragueCzech Republic
- Czech Academy of SciencesBiology Centre, Institute of EntomologyČeské BudějoviceCzech Republic
| | - Guin Zambatis
- Scientific Services, South African National ParksSkukuzaSouth Africa
| | - Petr Pyšek
- Department of Invasion EcologyCzech Academy of Sciences, Institute of BotanyPrůhoniceCzech Republic
- Department of Ecology, Faculty of ScienceCharles UniversityPragueCzech Republic
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2
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Liu C, Gauthier G, Gignac C, Lévesque E, Rochefort L. Scale-dependent effects of herbivory on moss communities in Arctic wetlands: A 25-year experiment. Ecol Evol 2024; 14:e11272. [PMID: 38665892 PMCID: PMC11043830 DOI: 10.1002/ece3.11272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 03/17/2024] [Accepted: 04/01/2024] [Indexed: 04/28/2024] Open
Abstract
Arctic ecosystems are undergoing rapid changes, including increasing disturbance by herbivore populations, which can affect plant species coexistence and community assemblages. Although the significance of mosses in Arctic wetlands is well recognized, the long-term influence of medium-sized herbivores on the composition of moss communities has received limited attention. We used data from a long-term (25 years) Greater Snow Goose (Anser caerulescens atlanticus) exclusion experiment in Arctic tundra wetlands to assess changes in the composition of moss communities at multiple spatial scales (cell, 4 cm2; quadrat, 100 cm2; exclosure, 16 m2). We investigated how snow goose grazing and grubbing can alter the composition of the moss community by measuring changes in alpha and beta diversity, as well as in the strength of plant interspecific interactions between moss species. Our results indicate that goose foraging significantly increased species diversity (richness, evenness, and inverse Simpson index) of moss communities at the cell and quadrat scales but not the exclosure scale. Goose foraging reduced the dissimilarity (beta diversity) of moss communities at all three scales, mainly due to decreased species turnover. Furthermore, goose foraging increased positive interaction between moss species pairs. These findings emphasize the critical role of geese in promoting moss species coexistence and increasing homogeneity in Arctic wetlands. This study illustrates how top-down regulation by herbivores can alter plant communities in Arctic wetlands and highlights the importance of considering herbivores when examining the response of Arctic plant biodiversity to future climate change.
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Affiliation(s)
- Chao Liu
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
| | - Gilles Gauthier
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de BiologieUniversité LavalQuébecQuébecCanada
| | - Charles Gignac
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
| | - Esther Lévesque
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Laboratoire d'Écologie Végétale Fonctionnelle (LEAF), Département des Sciences de l'EnvironnementUniversité du Québec à Trois‐RivièresTrois‐RivièresQuébecCanada
| | - Line Rochefort
- Centre d'études NordiquesUniversité LavalQuébecQuébecCanada
- Département de PhytologieUniversité LavalQuébecQuébecCanada
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Albrecht J, Wappler T, Fritz SA, Schleuning M. Fossil leaves reveal drivers of herbivore functional diversity during the Cenozoic. Proc Natl Acad Sci U S A 2023; 120:e2300514120. [PMID: 37523540 PMCID: PMC10410718 DOI: 10.1073/pnas.2300514120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/09/2023] [Indexed: 08/02/2023] Open
Abstract
Herbivorous arthropods are the most diverse group of multicellular organisms on Earth. The most discussed drivers of their inordinate taxonomic and functional diversity are high niche availability associated with the diversity of host plants and dense niche packing due to host partitioning among herbivores. However, the relative contributions of these two factors to dynamics in the diversity of herbivores throughout Earth's history remain unresolved. Using fossil data on herbivore-induced leaf damage from across the Cenozoic, we infer quantitative bipartite interaction networks between plants and functional feeding types of herbivores. We fit a general model of diversity to these interaction networks and discover that host partitioning among functional groups of herbivores contributed twice as much to herbivore functional diversity as host diversity. These findings indicate that niche packing primarily shaped the dynamics in the functional diversity of herbivores during the past 66 my. Our study highlights how the fossil record can be used to test fundamental theories of biodiversity and represents a benchmark for assessing the drivers of herbivore functional diversity in modern ecosystems.
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Affiliation(s)
- Jörg Albrecht
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main60325, Germany
| | - Torsten Wappler
- Natural History Department, Hessian State Museum, Darmstadt64283, Germany
- Department of Palaeontology, Institute of Geosciences, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn53115, Germany
| | - Susanne A. Fritz
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main60325, Germany
- Institut für Geowissenschaften, Goethe-Universität Frankfurt, Frankfurt am Main60438, Germany
| | - Matthias Schleuning
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main60325, Germany
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Teodoro-Paulo J, Alba JM, Charlesworth S, Kant MR, Magalhães S, Duncan AB. Intraspecific variation for host immune activation by the spider mite Tetranychus evansi. R Soc Open Sci 2023; 10:230525. [PMID: 37325599 PMCID: PMC10265008 DOI: 10.1098/rsos.230525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/12/2023] [Indexed: 06/17/2023]
Abstract
Many parasites can interfere with their host's defences to maximize their fitness. Here, we investigated if there is heritable variation in the spider mite Tetranychus evansi for traits associated with how they interact with their host plant. We also determined if this variation correlates with mite fecundity. Tetranychus evansi can interfere with jasmonate (JA) defences which are the main determinant of anti-herbivore immunity in plants. We investigated (i) variation in fecundity in the presence and absence of JA defences, making use of a wild-type tomato cultivar and a JA-deficient mutant (defenseless-1), and (ii) variation in the induction of JA defences, in four T. evansi field populations and 59 inbred lines created from an outbred population originating from controlled crosses of the four field populations. We observed a strong positive genetic correlation between fecundity in the presence (on wild-type) and the absence of JA defences (on defenseless-1). However, fecundity did not correlate with the magnitude of induced JA defences in wild-type plants. Our results suggest that the performance of the specialist T. evansi is not related to their ability to manipulate plant defences, either because all lines can adequately reduce levels of defences, or because they are resistant to them.
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Affiliation(s)
- Jéssica Teodoro-Paulo
- cE3c—Centre for Ecology, Evolution and Environmental Changes & CHANGE—Global Change and Sustainability Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
- Institut des Sciences de l’Évolution, University of Montpellier, CNRS, IRD, Montpellier, France
| | - Juan M. Alba
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Steven Charlesworth
- cE3c—Centre for Ecology, Evolution and Environmental Changes & CHANGE—Global Change and Sustainability Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Merijn R. Kant
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Sara Magalhães
- cE3c—Centre for Ecology, Evolution and Environmental Changes & CHANGE—Global Change and Sustainability Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Alison B. Duncan
- Institut des Sciences de l’Évolution, University of Montpellier, CNRS, IRD, Montpellier, France
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Affiliation(s)
- David M Braun
- Division of Plant Science & Technology, Division of Biological Sciences, Missouri Maize Center, Interdisciplinary Plant Group, University of Missouri, Columbia, MO 65211, USA
| | - Jacob D Washburn
- United States Department of Agriculture, Agricultural Research Service, 302-A Curtis Hall, Columbia, MO 65211, USA
| | - Jeffrey D Wood
- School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
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Pelaez JN, Gloss AD, Goldman-Huertas B, Kim B, Lapoint RT, Pimentel-Solorio G, Verster KI, Aguilar JM, Dittrich ACN, Singhal M, Suzuki HC, Matsunaga T, Armstrong EE, Charboneau JL, Groen SC, Hembry DH, Ochoa CJ, O’Connor TK, Prost S, Zaaijer S, Nabity PD, Wang J, Rodas E, Liang I, Whiteman NK. Evolution of chemosensory and detoxification gene families across herbivorous Drosophilidae. bioRxiv 2023:2023.03.16.532987. [PMID: 36993186 PMCID: PMC10055167 DOI: 10.1101/2023.03.16.532987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Herbivorous insects are exceptionally diverse, accounting for a quarter of all known eukaryotic species, but the genetic basis of adaptations that enabled this dietary transition remains poorly understood. Many studies have suggested that expansions and contractions of chemosensory and detoxification gene families - genes directly mediating interactions with plant chemical defenses - underlie successful plant colonization. However, this hypothesis has been challenging to test because the origins of herbivory in many lineages are ancient (>150 million years ago [mya]), obscuring genomic evolutionary patterns. Here, we characterized chemosensory and detoxification gene family evolution across Scaptomyza, a genus nested within Drosophila that includes a recently derived (<15 mya) herbivore lineage of mustard (Brassicales) specialists and carnation (Caryophyllaceae) specialists, and several non-herbivorous species. Comparative genomic analyses revealed that herbivorous Scaptomyza have among the smallest chemosensory and detoxification gene repertoires across 12 drosophilid species surveyed. Rates of gene turnover averaged across the herbivore clade were significantly higher than background rates in over half of the surveyed gene families. However, gene turnover was more limited along the ancestral herbivore branch, with only gustatory receptors and odorant binding proteins experiencing strong losses. The genes most significantly impacted by gene loss, duplication, or changes in selective constraint were those involved in detecting compounds associated with feeding on plants (bitter or electrophilic phytotoxins) or their ancestral diet (yeast and fruit volatiles). These results provide insight into the molecular and evolutionary mechanisms of plant-feeding adaptations and highlight strong gene candidates that have also been linked to other dietary transitions in Drosophila .
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Affiliation(s)
- Julianne N. Pelaez
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Brandeis University, Waltham, MA 02453, USA
| | - Andrew D. Gloss
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
| | - Benjamin Goldman-Huertas
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Bernard Kim
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Richard T. Lapoint
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- National Center for Biotechnology Information, Bethesda, MD 20894, USA
| | | | - Kirsten I. Verster
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Jessica M. Aguilar
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Anna C. Nelson Dittrich
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Boyce Thompson Institute, Ithaca NY 14853 USA
| | - Malvika Singhal
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Chemistry & Biochemistry, University of Oregon, OR, CA 97403, USA
| | - Hiromu C. Suzuki
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Teruyuki Matsunaga
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | | | - Joseph L.M. Charboneau
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
| | - Simon C. Groen
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology and Center for Genomics and Systems Biology, New York University, New York, NY 10003, USA
- Department of Nematology, University of California-Riverside, Riverside, CA 92521, USA
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, CA 92521, USA
- Center for Plant Cell Biology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, CA 92521, USA
| | - David H. Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Biology, University of Texas Permian Basin, Odessa, TX 79762, USA
| | - Christopher J. Ochoa
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Molecular Biology Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
| | - Timothy K. O’Connor
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Stefan Prost
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Biology, Stanford University, Palo Alto, CA 94305, USA
| | - Sophie Zaaijer
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Jacobs Institute, Cornell Tech, New York, NY 10044, USA
- FIND Genomics, New York, NY 10044, USA
| | - Paul D. Nabity
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
- Department of Botany and Plant Sciences, University of California-Riverside, Riverside, CA 92521, USA
| | - Jiarui Wang
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90007, USA
| | - Esteban Rodas
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Irene Liang
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
| | - Noah K. Whiteman
- Department of Integrative Biology, University of California-Berkeley, Berkeley, CA 94720, USA
- Department of Molecular and Cell Biology, University of California-Berkeley, Berkeley, CA 94720, USA
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Kalske A, Kessler A. Herbivory selects for tolerance and constitutive defence across stages of community succession. Proc Biol Sci 2023; 290:20222458. [PMID: 36787795 PMCID: PMC9928524 DOI: 10.1098/rspb.2022.2458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 01/13/2023] [Indexed: 02/16/2023] Open
Abstract
Plants defend themselves from herbivory by either reducing damage (resistance) or minimizing its negative fitness effects with compensatory growth (tolerance). Herbivore pressure can fluctuate from year to year in an early secondary successional community, which can create temporal variation in selection for defence traits. We manipulated insect herbivory and successional age of the community as agents of natural selection in replicated common gardens with the perennial herb Solidago altissima. In these genotypic selection experiments, herbivory consistently selected for better defended plants in both successional communities. Herbivore suppression increased plant survival and the probability of flowering only in mid-succession. Despite these substantial differences in the effects of herbivory between early and mid-succession, the selection on defence traits did not change. Succession affected selection only on aboveground biomass, with positive selection in early but not mid-succession, suggesting an important role of competition in the selective environment. These results demonstrate that changes in the community that affect key life-history traits in an individual species can occur over very short timescales in a dynamic secondary successional environment. The resulting community context-driven variation in natural selection may be an important, yet overlooked, contributor to adaptive mosaics across populations.
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Affiliation(s)
- Aino Kalske
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - André Kessler
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
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Houadria MYI, Barone G, Fayle TM, Schmitt T, Konik P, Feldhaar H. An experimental, behavioral, and chemical analysis of food limitations in mutualistic Crematogaster ant symbionts inhabiting Macaranga host plants. Ecol Evol 2023; 13:e9760. [PMID: 36778840 PMCID: PMC9905419 DOI: 10.1002/ece3.9760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 02/11/2023] Open
Abstract
Obligate mutualistic plant-ants are often constrained by their plant partner's capacity to provide resources. However, despite this limitation, some ant partners actively reject potential prey items and instead drop them from the plant rather than consuming them, leaving the ants entirely reliant on host plant-provided food, including that provided indirectly by the symbiotic scale insects that ants tend inside the plants. This dependency potentially increases the efficiency of these ants in defending their host. We hypothesize that if this ant behavior was beneficial to the symbiosis, prey rejection by ants would be observed across multiple plant host species. We also hypothesize that plant-provided food items and symbiotic scale insects from other ant plants should be rejected. We address these hypotheses in the Crematogaster ant-Macaranga plant system, in which plants provide living space and food, while ants protect plants from herbivory. We observed food acceptance and rejection behavior across five ant species and three plant host species. Ants were offered three types of food: termites as a surrogate herbivore, symbiotic scale insects, and nutritious food bodies (FB) produced by different host plant species. The unique ant species living in M. winkleri was the most likely to reject food items not provided by the plant species, followed by ants in M. glandibracteolata, while ants in M. pearsonii accepted most items offered to them. Using stable isotopes, chemical cues, and proteomic analyses, we demonstrate that this behavior was not related to differences between plant species in nutritional quality or composition of FB. Isotopic signatures revealed that certain species are primary consumers but other ant species can be secondary consumers even where surrogate herbivores are rejected, although these values varied depending on the ant developmental stage and plant species. Macaranga pearsonii and M. glandibracteolata, the two most closely related plant species, had most similar surface chemical cues of FB. However, M. glandibracteolata had strongest differences in food body nutritional content, isotopic signatures, and protein composition from either of the other two plant species studied. Taken together we believe our results point toward potential host coercion of symbiont ants by plants in the genus Macaranga Thouars (Euphorbiaceae).
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Affiliation(s)
- Mickal Y. I. Houadria
- Biology Centre of the Czech Academy of SciencesInstitute of EntomologyCeske BudejoviceCzech Republic
| | - Giulio Barone
- Department of Agricultural, Food and Forest SciencesUniversity of PalermoPalermoItaly
| | - Tom M. Fayle
- Biology Centre of the Czech Academy of SciencesInstitute of EntomologyCeske BudejoviceCzech Republic,School of Biological and Behavioural SciencesQueen Mary University of LondonLondonUK
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical Biology, BiocentreUniversity of WürzburgWürzburgGermany
| | - Petr Konik
- Department of Chemistry, Faculty of ScienceUniversity of South Bohemia in Ceske BudejoviceCeske BudejoviceCzech Republic
| | - Heike Feldhaar
- Animal Population Ecology, Animal Ecology I, Bayreuth Center of Ecology and Environmental Research (BayCEER)University of BayreuthBayreuthGermany
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9
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Johnson SN, Cibils-Stewart X, Waterman JM, Biru FN, Rowe RC, Hartley SE. Elevated atmospheric CO 2 changes defence allocation in wheat but herbivore resistance persists. Proc Biol Sci 2022; 289:20212536. [PMID: 35168395 PMCID: PMC8848237 DOI: 10.1098/rspb.2021.2536] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Predicting how plants allocate to different anti-herbivore defences in response to elevated carbon dioxide (CO2) concentrations is important for understanding future patterns of crop susceptibility to herbivory. Theories of defence allocation, especially in the context of environmental change, largely overlook the role of silicon (Si), despite it being the major anti-herbivore defence in the Poaceae. We demonstrated that elevated levels of atmospheric CO2 (e[CO2]) promoted plant growth by 33% and caused wheat (Triticum aestivum) to switch from Si (-19%) to phenolic (+44%) defences. Despite the lower levels of Si under e[CO2], resistance to the global pest Helicoverpa armigera persisted; relative growth rates (RGRs) were reduced by at least 33% on Si-supplied plants, irrespective of CO2 levels. RGR was negatively correlated with leaf Si concentrations. Mandible wear was c. 30% higher when feeding on Si-supplemented plants compared to those feeding on plants with no Si supply. We conclude that higher carbon availability under e[CO2] reduces silicification and causes wheat to increase concentrations of phenolics. However, Si supply, at all levels, suppressed the growth of H. armigera under both CO2 regimes, suggesting that shifts in defence allocation under future climate change may not compromise herbivore resistance in wheat.
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Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Ximena Cibils-Stewart
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia,Instituto Nacional de Investigación Agropecuaria (INIA), La Estanzuela Research Station, Ruta 50, Km. 11, Colonia, Uruguay
| | - Jamie M. Waterman
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Fikadu N. Biru
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia,College of Agriculture and Veterinary Medicine, Jimma University, Jimma 307, Ethiopia
| | - Rhiannon C. Rowe
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
| | - Susan E. Hartley
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
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Denton EM, Pyle LA, Sheley RL. Seedling defoliation may enhance survival of dominant wheatgrasses but not Poa secunda seeded for restoration in the sagebrush steppe of the Northern Great Basin. AoB Plants 2021; 13:plab047. [PMID: 34457229 PMCID: PMC8387967 DOI: 10.1093/aobpla/plab047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
Restoration of dryland ecosystems is often limited by low seedling establishment and survival. Defoliation caused by insects and small mammals could be an overlooked cause of seedling mortality. In the sagebrush steppe, we examined the effect of seedling defoliation on the survival of perennial grasses commonly used as restoration materials. Under field conditions, seedlings of three perennial bunchgrass species (non-native Agropyron cristatum, and native grasses Poa secunda and Pseudoroegneria spicata) were defoliated at two intensities (30 % and 70 % leaf length removal) and frequencies (one or two clippings) and compared to a non-defoliated control. Following emergence the first year, clippings occurred at the two-leaf stage; a second clipping occurred 1 month later for repeated defoliation treatments. We monitored seedling survival and tillering for 2 years. We expected higher defoliation intensity and frequency to reduce survival for all species, but only a few treatments reduced Po. secunda survival. Conversely, larger-statured Triticeae (wheatgrasses) benefited from some defoliation treatments. In both years, A. cristatum survival increased with repeated defoliation at both intensities. Defoliation did not affect Ps. spicata survival in the first year, but a single defoliation in the second year resulted in increased survival. In both A. cristatum and Ps. spicata, higher-intensity defoliation reduced the boost to survival resulting from defoliation frequency. Seedlings with more tillers had greater survival probabilities, but tiller number was unaffected by defoliation. Further research may elucidate mechanisms seedlings use to compensate for or benefit from defoliation. In the meantime, managers should aim to select defoliation-tolerant species if they anticipate herbivory will be problematic for restoration sites.
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Affiliation(s)
- Elsie M Denton
- Eastern Oregon Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, Burns, 67826A Highway 205, OR 97720, USA
| | - Lysandra A Pyle
- Eastern Oregon Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, Burns, 67826A Highway 205, OR 97720, USA
- Sierra Foothills Research and Extension Center, University of California, Division of Agriculture and Natural Resources, Browns Valley, 8279 Scott Forbes Rd, CA 95918, USA
- Department of Plant Sciences, University of Saskatchewan, Saskatoon, 51 Campus Dr., Saskatchewan S7N 5A8, Canada
| | - Roger L Sheley
- Eastern Oregon Agricultural Research Center, United States Department of Agriculture, Agricultural Research Service, Burns, 67826A Highway 205, OR 97720, USA
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11
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Ferreira PPDS, Rodrigues D. Performance of Danaini larvae is affected by both exotic host plants and abiotic conditions. Ecol Evol 2021; 11:9876-9886. [PMID: 34306670 PMCID: PMC8293738 DOI: 10.1002/ece3.7821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/31/2021] [Accepted: 06/06/2021] [Indexed: 12/03/2022] Open
Abstract
The consequences of the introduction of invasive plants for the diet of herbivorous insects have been little explored in nature where, potentially, abiotic and biotic factors operate. In this study, we examined the larval performance of two Neotropical Danaini butterflies when using either a native or an exotic Apocynaceae species as host plant in both field and laboratory experiments. Hosts greatly differ in their amount of latex exudation and other physicochemical traits, as well as in the amount of evolutionary time they have interacted with herbivores. First, herbivore performance on the hosts was investigated under laboratory conditions. Larvae of both Danaini species took more time to develop on the exotic host; larval survivorship did not vary between hosts. Second, first instar survivorship on both hosts was evaluated in two field sites, one site per host. To do so, in both sites half of the larvae were bagged (protected against both abiotic and biotic factors) while the remainder were nonbagged (exposed). The interaction between larval exposure with the use of the exotic host reduced larval survival. We concluded that the combined effects of host plant traits and abiotic factors reduced survival of herbivores in field conditions. Therefore, the performance of herbivores when using hosts of different origins should be considered together with the multiple ecological factors found in natural environments, as these factors can modify the result of plant-herbivore interactions.
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Affiliation(s)
- Pedro Paulo da Silva Ferreira
- Programa de Pós‐Graduação em EcologiaInstituto de BiologiaUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Daniela Rodrigues
- Programa de Pós‐Graduação em EcologiaInstituto de BiologiaUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
- Laboratório de Interações Inseto‐PlantaDepartamento de EcologiaInstituto de BiologiaUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
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12
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Goldberg JK, Sternlieb SR, Pintel G, Delph LF. Observational evidence of herbivore-specific associational effects between neighboring conspecifics in natural, dimorphic populations of Datura wrightii. Ecol Evol 2021; 11:5547-5561. [PMID: 34026028 PMCID: PMC8131817 DOI: 10.1002/ece3.7454] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 02/11/2021] [Accepted: 02/19/2021] [Indexed: 11/06/2022] Open
Abstract
Associational effects-in which the vulnerability of a plant to herbivores is influenced by its neighbors-have been widely implicated in mediating plant-herbivore interactions. Studies of associational effects typically focus on interspecific interactions or pest-crop dynamics. However, associational effects may also be important for species with intraspecific variation in defensive traits. In this study, we observed hundreds of Datura wrightii-which exhibits dimorphism in its trichome phenotype-from over 30 dimorphic populations across California. Our aim was to determine whether a relationship existed between the trichome phenotype of neighboring conspecifics and the likelihood of being damaged by four species of herbivorous insects. We visited plants at three timepoints to assess how these effects vary both within and between growing seasons. We hypothesized that the pattern of associational effects would provide rare morphs (i.e., focal plants that are a different morph than their neighbors) with an advantage in the form of reduced herbivory, thereby contributing to the negative frequency-dependent selection previously documented in this system. We found the best predictor of herbivory/herbivore presence on focal plants was the phenotype of the focal plant. However, we also found some important neighborhood effects. The total number of plants near a focal individual predicted the likelihood and/or magnitude of herbivory by Tupiochoris notatus, Lema daturaphila, and Manduca sexta. We also found that velvety focal plants with primarily sticky neighbors are more susceptible to infestation by Tupiochoris notatus and Lema daturaphila. This does not align with the hypothesis that associational effects at the near-neighbor scale contribute to a rare-morph advantage in this system. Overall, the results of our study show that the number and trichome-morph composition of neighboring conspecifics impact interactions between D. wrightii and insect herbivores.
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Affiliation(s)
- Jay K. Goldberg
- Department of BiologyIndiana UniversityBloomingtonINUSA
- Department of Ecology and Evolutionary BiologyUniversity of ArizonaTucsonAZUSA
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13
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Abstract
Deer are regarded to be a keystone species as they play a crucial role in the way an ecosystem functions. Most deer-forest interaction studies apply a single scale - process of analyzing ecological interactions by only taking into account one dependent variable - to understand how deer browsing behavior shapes different forest components, but they overlook the fact that forests respond to multiple scales simultaneously. This research evaluates the effect of browsing by wild deer on temperate and boreal forests at different scales by synthesizing seminal papers, specifically (a) what are the effects of deer population density in forest regeneration? (b) What are the effects of deer when forests present diverging spatial characteristics? (c) What are the effects on vegetation at different temporal scales? and (d) What are the hierarchical effects of deer when considering other trophic levels? Additionally, a framework based on modern technology is proposed to answer the multiscale research questions previously identified. When analyzing deer-forest interactions at different scales, the strongest relationships occur at the extremes. For example: when deer assemblage occurs in low or high density and is composed of a mix of small and large species. As forests on poor soils remain restrained in size, isolated and chronically browsed. When forests harbor incomplete trophic levels, the effects spill over to lower trophic levels. To better understand the complexities in deer-forest interactions, researchers should combine technology-based instruments like fixed sensors and drones with field-tested methods such observational studies and experiments to tackle multiscale research questions.
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Affiliation(s)
- Juan Ignacio Ramirez
- Department of Ecology and Environmental SciencesUmeå UniversityUmeåSweden
- Environmental Science GroupUniversity & ResearchWageningenthe Netherlands
- Colegio de Ciencias Biológicas y Ambientales COCIBAUniversidad San Francisco de Quito USFQQuitoEcuador
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14
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Thakur MP, Künne T, Unsicker SB, Biere A, Ferlian O, Pruschitzki U, Thouvenot L, Türke M, Eisenhauer N. Invasive earthworms reduce chemical defense and increase herbivory and pathogen infection in native trees. J Ecol 2021; 109:763-775. [PMID: 33664527 PMCID: PMC7891629 DOI: 10.1111/1365-2745.13504] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 09/01/2020] [Indexed: 05/24/2023]
Abstract
Recent research shows that earthworms can alter defense traits of plants against herbivores and pathogens by affecting soil biochemistry. Yet, the effects of invasive earthworms on defense traits of native plants from previously earthworm-free ecosystems as well as the consequences for multitrophic interactions are virtually unknown.Here we use a combination of an observational study and a complementary experimental study to investigate the effects of invasive earthworms on leaf defense traits, herbivore damage and pathogen infection in two poplar tree species (Populus balsamifera and Populus tremuloides) native to North American boreal forests.Our observational study showed that earthworm invasion was associated with enhanced leaf herbivory (by leaf-chewing insects) in saplings of both tree species. However, we only detected significant shifts in the concentration of chemical defense compounds in response to earthworm invasion for P. balsamifera. Specifically, leaf phenolic concentrations, including salicinoids and catechin, were lower in P. balsamifera from earthworm-invaded sites.Our experimental study confirmed an earthworm-induced reduction in leaf defense levels in P. balsamifera for one of the defense compounds, tremulacin. The experimental study additionally showed that invasive earthworms reduced leaf dry matter content, potentially increasing leaf palatability, and enhanced susceptibility of trees to infection by a fungal pathogen, but not to aphid infestation, in the same tree species. Synthesis. Our results show that invasive earthworms can decrease the concentrations of some chemical defense compounds in P. balsamifera, which could make them susceptible to leaf-chewing insects. Such potential impacts of invasive earthworms are likely to have implications for tree survival and competition, native tree biodiversity and ecosystem functioning.
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Affiliation(s)
- Madhav P. Thakur
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
- Department of Terrestrial EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
- Terrestrial Ecology GroupInstitute of Ecology and EvolutionUniversity of BernBernSwitzerland
| | - Tom Künne
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
| | - Sybille B. Unsicker
- Department of BiochemistryMax Planck Institute for Chemical EcologyJenaGermany
| | - Arjen Biere
- Department of Terrestrial EcologyNetherlands Institute of Ecology (NIOO‐KNAW)WageningenThe Netherlands
| | - Olga Ferlian
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Ulrich Pruschitzki
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Lise Thouvenot
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Manfred Türke
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
| | - Nico Eisenhauer
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
- Institute of BiologyLeipzig UniversityLeipzigGermany
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15
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Song X, Corlett RT. Enemies mediate distance- and density-dependent mortality of tree seeds and seedlings: a meta-analysis of fungicide, insecticide and exclosure studies. Proc Biol Sci 2021; 288:20202352. [PMID: 33468003 DOI: 10.1098/rspb.2020.2352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Conspecific negative distance- and density-dependence is often assumed to be one of the most important mechanisms controlling forest community assembly and species diversity globally. Plant pathogens, and insect and mammalian herbivores, are the most common natural enemy types that have been implicated in this phenomenon, but their general effects at different plant life stages are still unclear. Here, we conduct a meta-analysis of studies that involved robust manipulative experiments, using fungicides, insecticides and exclosures, to assess the contributions of different natural enemy types to distance- and density-dependent effects at seed and seedling stages. We found that distance- and density-dependent mortality caused by natural enemies was most likely at the seedling stage and was greater at higher mean annual temperatures. Conspecific negative distance- and density-dependence at the seedling stage is significantly weakened when fungicides were applied. By contrast, negative conspecific distance- and density-dependence is not a general pattern at the seed stage. High seed mass reduced distance- and density-dependent mortality at the seed stage. Seed studies excluding only large mammals found significant negative conspecific distance-dependent mortality, but exclusion of all mammals resulted in a non-significant effect of conspecifics. Our study suggests that plant pathogens are a major cause of distance- and density-dependent mortality at the seedling stage, while the impacts of herbivores on seedlings have been understudied. At the seed stage, large and small mammals, respectively, weaken and enhance negative conspecific distance-dependent mortality. Future research should identify specific agents of mortality, investigate the interactions among different enemy types and assess how global change may affect natural enemies and thus influence the strength of conspecific distance- and density-dependence.
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Affiliation(s)
- Xiaoyang Song
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, People's Republic of China.,Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, People's Republic of China
| | - Richard T Corlett
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Mengla 666303, People's Republic of China.,Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, People's Republic of China
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16
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Castaño C, Camarero JJ, Zas R, Sampedro L, Bonet JA, Alday JG, Oliva J. Insect defoliation is linked to a decrease in soil ectomycorrhizal biomass and shifts in needle endophytic communities. Tree Physiol 2020; 40:1712-1725. [PMID: 32785638 DOI: 10.1093/treephys/tpaa104] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 08/07/2020] [Indexed: 06/11/2023]
Abstract
Insect outbreaks of increasing frequency and severity in forests are predicted due to climate change. Insect herbivory is known to promote physiological changes in forest trees. However, little is known about whether these plant phenotypic adjustments have cascading effects on tree microbial symbionts such as fungi in roots and foliage. We studied the impact of defoliation by the pine processionary moth in two infested Pinus nigra forests through a multilevel sampling of defoliated and non-defoliated trees. We measured tree growth, nutritional status and carbon allocation to chemical defenses. Simultaneously, we analysed the putative impact of defoliation on the needle endophytes and on the soil fungal communities. Higher concentrations of chemical defenses were found in defoliated trees, likely as a response to defoliation; however, no differences in non-structural carbohydrate reserves were found. In parallel to the reductions in tree growth and changes in chemical defenses, we observed shifts in the composition of needle endophytic and soil fungal communities in defoliated trees. Defoliated trees consistently corresponded with a lower biomass of ectomycorrhizal fungi in both sites, and a higher alpha diversity and greater relative abundance of belowground saprotrophs and pathogens. However, ectomycorrhizal alpha diversity was similar between non-defoliated and defoliated trees. Specific needle endophytes in old needles were strongly associated with non-defoliated trees. The potential role of these endophytic fungi in pine resistance should be further investigated. Our study suggests that lower biomass of ectomycorrhizal fungi in defoliated trees might slow down tree recovery since fungal shifts might affect tree-mycorrhizal feedbacks and can potentially influence carbon and nitrogen cycling in forest soils.
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Affiliation(s)
- Carles Castaño
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden
| | - J Julio Camarero
- Instituto Pirenaico de Ecología (IPE-CSIC), 50192 Zaragoza, Spain
| | - Rafael Zas
- Misión Biológica de Galicia, Consejo Superior de Investigaciones Científicas (MBG-CSIC), Apdo 28, 36080 Pontevedra, Spain
| | - Luis Sampedro
- Misión Biológica de Galicia, Consejo Superior de Investigaciones Científicas (MBG-CSIC), Apdo 28, 36080 Pontevedra, Spain
| | - José Antonio Bonet
- Departament de Producció Vegetal i Ciència Forestal, Universitat de Lleida, Av. Rovira Roure, 191, E-25198 Lleida, Spain
- Joint Research Unit CTFC - AGROTECNIO, Av. Alcalde Rovira Roure 191, E25198 Lleida, Spain
| | - Josu G Alday
- Departament de Producció Vegetal i Ciència Forestal, Universitat de Lleida, Av. Rovira Roure, 191, E-25198 Lleida, Spain
- Joint Research Unit CTFC - AGROTECNIO, Av. Alcalde Rovira Roure 191, E25198 Lleida, Spain
| | - Jonàs Oliva
- Departament de Producció Vegetal i Ciència Forestal, Universitat de Lleida, Av. Rovira Roure, 191, E-25198 Lleida, Spain
- Joint Research Unit CTFC - AGROTECNIO, Av. Alcalde Rovira Roure 191, E25198 Lleida, Spain
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17
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Lucero JE, Arab NM, Meyer ST, Pal RW, Fletcher RA, Nagy DU, Callaway RM, Weisser WW. Escape from natural enemies depends on the enemies, the invader, and competition. Ecol Evol 2020; 10:10818-10828. [PMID: 33072298 PMCID: PMC7548199 DOI: 10.1002/ece3.6737] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/05/2020] [Accepted: 06/29/2020] [Indexed: 11/19/2022] Open
Abstract
The enemy release hypothesis (ERH) attributes the success of some exotic plant species to reduced top‐down effects of natural enemies in the non‐native range relative to the native range. Many studies have tested this idea, but very few have considered the simultaneous effects of multiple kinds of enemies on more than one invasive species in both the native and non‐native ranges. Here, we examined the effects of two important groups of natural enemies–insect herbivores and soil biota–on the performance of Tanacetum vulgare (native to Europe but invasive in the USA) and Solidago canadensis (native to the USA but invasive in Europe) in their native and non‐native ranges, and in the presence and absence of competition. In the field, we replicated full‐factorial experiments that crossed insecticide, T. vulgare–S. canadensis competition, and biogeographic range (Europe vs. USA) treatments. In greenhouses, we replicated full‐factorial experiments that crossed soil sterilization, plant–soil feedback, and biogeographic range treatments. We evaluated the effects of experimental treatments on T. vulgare and S. canadensis biomass. The effects of natural enemies were idiosyncratic. In the non‐native range and relative to populations in the native range, T. vulgare escaped the negative effects of insect herbivores but not soil biota, depending upon the presence of S. canadensis; and S. canadensis escaped the negative effects of soil biota but not insect herbivores, regardless of competition. Thus, biogeographic escape from natural enemies depended upon the enemies, the invader, and competition.
Synthesis: By explicitly testing the ERH in terms of more than one kind of enemy, more than one invader, and more than one continent, this study enhances our nuanced perspective of how natural enemies can influence the performance of invasive species in their native and non‐native ranges.
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Affiliation(s)
| | - Nafiseh Mahdavi Arab
- Terrestrial Ecology Research Group Department of Ecology and Ecosystem Management School of Life Sciences Weihenstephan Technical University of Munich Freising Germany
| | - Sebastian T Meyer
- Terrestrial Ecology Research Group Department of Ecology and Ecosystem Management School of Life Sciences Weihenstephan Technical University of Munich Freising Germany
| | - Robert W Pal
- Department of Biological Sciences Montana Technological University Butte MT USA.,Institute of Biology Faculty of Sciences University of Pecs Pecs Hungary
| | - Rebecca A Fletcher
- School of Plant and Environmental Sciences Virginia Tech Blacksburg VA USA
| | - David U Nagy
- Institute of Biology Faculty of Sciences University of Pecs Pecs Hungary
| | - Ragan M Callaway
- Divison of Biological Sciences and the Institute on Ecosystems University of Montana Missoula MT USA
| | - Wolfgang W Weisser
- Terrestrial Ecology Research Group Department of Ecology and Ecosystem Management School of Life Sciences Weihenstephan Technical University of Munich Freising Germany
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18
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Cushman JH, Saunders LE, Refsland TK. Long-term and interactive effects of different mammalian consumers on growth, survival, and recruitment of dominant tree species. Ecol Evol 2020; 10:8801-8814. [PMID: 32884658 PMCID: PMC7452786 DOI: 10.1002/ece3.6578] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/15/2020] [Accepted: 06/18/2020] [Indexed: 11/19/2022] Open
Abstract
Throughout the world, numerous tree species are reported to be in decline, either due to increased mortality of established trees or reduced recruitment. The situation appears especially acute for oaks, which are dominant features of many landscapes in the northern hemisphere. Although numerous factors have been hypothesized to explain reductions in tree performance, vertebrate herbivores and granivores may serve as important drivers of these changes. Here, using data from 8- and 14-year-old exclosure experiments, we evaluated the individual and interactive effects of large and small mammalian herbivores on the performance of three widespread oak species in California-coast live oak (Quercus agrifolia), California black oak (Q. kelloggii), and Oregon white oak (Q. garryana). Although impacts varied somewhat by species and experiment, herbivory by black-tailed deer (Odocoileus hemionus columbianus) reduced the height and survival of juvenile coast live oaks and altered their architecture, as well as reduced the abundance of black oak seedlings, the richness of woody species and the cover of nonoak woody species. Small mammals (Microtus californicus and Peromyscus maniculatus) had even more widespread effects, reducing the abundance of black oak seedlings and the height and cover of all three oak species. We also detected numerous interactions between small mammals and deer, with one herbivore having positive or negative effects on oak abundance and cover when the other herbivore was either present or absent. For example, deer often had negative effects on seedling abundance only when, or even more so when, small mammals were present. In summary, mammalian consumers play crucial roles in limiting oak recruitment by reducing seedling abundance, maintaining trees in stunted states, and preventing them from reaching sapling stages and becoming reproductive. Interactions between large and small mammals can also alter the intensity and direction of their effects on trees.
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Affiliation(s)
- J. Hall Cushman
- Department of Natural Resources & Environmental ScienceUniversity of NevadaRenoNVUSA
| | | | - Tyler K. Refsland
- Department of Natural Resources & Environmental ScienceUniversity of NevadaRenoNVUSA
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19
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Brandenburger CR, Kim M, Slavich E, Meredith FL, Salminen J, Sherwin WB, Moles AT. Evolution of defense and herbivory in introduced plants-Testing enemy release using a known source population, herbivore trials, and time since introduction. Ecol Evol 2020; 10:5451-5463. [PMID: 32607166 PMCID: PMC7319247 DOI: 10.1002/ece3.6288] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/07/2020] [Accepted: 03/30/2020] [Indexed: 12/12/2022] Open
Abstract
The enemy release hypothesis is often cited as a potential explanation for the success of introduced plants; yet, empirical evidence for enemy release is mixed. We aimed to quantify changes in herbivory and defense in introduced plants while controlling for three factors that might have confounded past studies: using a wide native range for comparison with the introduced range, measuring defense traits without determining whether they affect herbivore preferences, and not considering the effect of time since introduction. The first hypothesis we tested was that introduced plants will have evolved lower levels of plant defense compared to their source population. We grew South African (source) and Australian (introduced) beach daisies (Arctotheca populifolia) in a common-environment glasshouse experiment and measured seven defense traits. Introduced plants had more ash, alkaloids, and leaf hairs than source plants, but were also less tough, with a lower C:N ratio and less phenolics. Overall, we found no difference in defense between source and introduced plants. To determine whether the feeding habits of herbivores align with changes in defense traits, we conducted preference feeding trials using five different herbivore species. Herbivores showed no overall preference for leaves from either group. The second hypothesis we tested was that herbivory on introduced plant species will increase through time after introduction to a new range. We recorded leaf damage on herbarium specimens of seven species introduced to eastern Australia and three native control species. We found no change in the overall level of herbivory experienced by introduced plants since arriving in Australia. CONCLUSION In the field of invasion ecology, we need to rethink the paradigm that species introduced to a new range undergo simple decreases in defenses against herbivores. Instead, plants are likely to employ a range of defense traits that evolve in both coordinated and opposing ways in response to a plethora of different biotic and abiotic selective pressures.
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Affiliation(s)
- Claire R. Brandenburger
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Martin Kim
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Eve Slavich
- Stats CentralMark Wainwright Analytical CentreUniversity of New South WalesSydneyNSWAustralia
| | - Floret L. Meredith
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Juha‐Pekka Salminen
- Natural Chemistry Research GroupDepartment of ChemistryUniversity of TurkuTurkuFinland
| | - William B. Sherwin
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Angela T. Moles
- Evolution and Ecology Research CentreSchool of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
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20
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Mesquita-Neto JN, Paiva EAS, Galetto L, Schlindwein C. Nectar Secretion of Floral Buds of Tococa guianensis Mediates Interactions With Generalist Ants That Reduce Florivory. Front Plant Sci 2020; 11:627. [PMID: 32508868 PMCID: PMC7253585 DOI: 10.3389/fpls.2020.00627] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
The specialised mutualism between Tococa guianensis and ants housed in its leaf domatia is a well-known example of myrmecophily. A pollination study on this species revealed that flowers in the bud stage exude a sugary solution that is collected by ants. Given the presence of this unexpected nectar secretion, we investigated how, where, and when floral buds of T. guianensis secret nectar and what function it serves. We studied a population of T. guianensis occurring in a swampy area in the Cerrado of Brazil by analyzing the chemical composition and secretion dynamics of the floral-bud nectar and the distribution and ultrastructure of secretory tissues. We also measured flower damage using ant-exclusion experiments. Floral bud nectar was secreted at the tip of the petals, which lack a typical glandular structure but possess distinctive mesophyll due to the presence of numerous calcium oxalate crystals. The nectar, the production of which ceased after flower opening, was composed mainly of sucrose and low amounts of glucose and fructose. Nectar was consumed by generalist ants and sporadically by stingless bees. Ant exclusion experiments resulted in significantly increased flower damage. The floral nectar of T. guianensis is produced during the bud stage. This bud-nectar has the extranuptial function of attracting generalist ants that reduce florivory. Pollen is the unique floral resource attracting pollinators during anthesis. Tococa guianensis, thus, establishes relationships with two functional groups of ant species: specialist ants acting against herbivory and generalist ants acting against florivory.
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Affiliation(s)
- José Neiva Mesquita-Neto
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Centro de Investigación en Estudios Avanzados del Maule, Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca, Chile
| | - Elder Antônio Sousa Paiva
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Leonardo Galetto
- Instituto Multidisciplinario de Biología Vegetal (UNC-CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Clemens Schlindwein
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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21
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Moreira X, Abdala-Roberts L, Bruun HH, Covelo F, De Frenne P, Galmán A, Gaytán Á, Jaatinen R, Pulkkinen P, Ten Hoopen JPJG, Timmermans BGH, Tack AJM, Castagneyrol B. Latitudinal variation in seed predation correlates with latitudinal variation in seed defensive and nutritional traits in a widespread oak species. Ann Bot 2020; 125:881-890. [PMID: 31858135 PMCID: PMC7218813 DOI: 10.1093/aob/mcz207] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 12/17/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND AND AIMS Classic theory on geographical gradients in plant-herbivore interactions assumes that herbivore pressure and plant defences increase towards warmer and more stable climates found at lower latitudes. However, the generality of these expectations has been recently called into question by conflicting empirical evidence. One possible explanation for this ambiguity is that most studies have reported on patterns of either herbivory or plant defences whereas few have measured both, thus preventing a full understanding of the implications of observed patterns for plant-herbivore interactions. In addition, studies have typically not measured climatic factors affecting plant-herbivore interactions, despite their expected influence on plant and herbivore traits. METHODS Here we tested for latitudinal variation in insect seed predation and seed traits putatively associated with insect attack across 36 Quercus robur populations distributed along a 20° latitudinal gradient. We then further investigated the associations between climatic factors, seed traits and seed predation to test for climate-based mechanisms of latitudinal variation in seed predation. KEY RESULTS We found strong but contrasting latitudinal clines in seed predation and seed traits, whereby seed predation increased whereas seed phenolics and phosphorus decreased towards lower latitudes. We also found a strong direct association between temperature and seed predation, with the latter increasing towards warmer climates. In addition, temperature was negatively associated with seed traits, with populations at warmer sites having lower levels of total phenolics and phosphorus. In turn, these negative associations between temperature and seed traits led to a positive indirect association between temperature and seed predation. CONCLUSIONS These results help unravel how plant-herbivore interactions play out along latitudinal gradients and expose the role of climate in driving these outcomes through its dual effects on plant defences and herbivores. Accordingly, this emphasizes the need to account for abiotic variation while testing concurrently for latitudinal variation in plant traits and herbivore pressure.
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Affiliation(s)
- Xoaquín Moreira
- Misión Biológica de Galicia (MBG-CSIC), Pontevedra, Galicia, Spain
| | - Luis Abdala-Roberts
- Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Itzimná, Mérida, Yucatán, Mexico
| | - Hans Henrik Bruun
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Felisa Covelo
- Departamento de Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, Sevilla, Spain
| | | | - Andrea Galmán
- Misión Biológica de Galicia (MBG-CSIC), Pontevedra, Galicia, Spain
| | - Álvaro Gaytán
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Raimo Jaatinen
- Natural Resources Institute Finland, Haapastensyrjä Breeding Station, Läyliäinen, Finland
| | - Pertti Pulkkinen
- Natural Resources Institute Finland, Haapastensyrjä Breeding Station, Läyliäinen, Finland
| | | | - Bart G H Timmermans
- Department of Agriculture, Louis Bolk Institute, LA Driebergen, the Netherlands
| | - Ayco J M Tack
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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22
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Bont Z, Pfander M, Robert CAM, Huber M, Poelman EH, Raaijmakers CE, Erb M. Adapted dandelions trade dispersal for germination upon root herbivore attack. Proc Biol Sci 2020; 287:20192930. [PMID: 32097589 DOI: 10.1098/rspb.2019.2930] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
A plant's offspring may escape unfavourable local conditions through seed dispersal. Whether plants use this strategy to escape insect herbivores is not well understood. Here, we explore how different dandelion (Taraxacum officinale agg.) populations, including diploid outcrossers and triploid apomicts, modify seed dispersal in response to root herbivore attack by their main root-feeding natural enemy, the larvae of the common cockchafer Melolontha melolontha. In a manipulative field experiment, root herbivore attack increased seed dispersal potential through a reduction in seed weight in populations that evolved under high root herbivore pressure, but not in populations that evolved under low pressure. This increase in dispersal potential was independent of plant cytotype, but associated with a reduction in germination rate, suggesting that adapted dandelions trade dispersal for establishment upon attack by root herbivores. Analysis of vegetative growth parameters suggested that the increased dispersal capacity was not the result of stress flowering. In summary, these results suggest that root herbivory selects for an induced increase in dispersal ability in response to herbivore attack. Induced seed dispersal may be a strategy that allows adapted plants to escape from herbivores.
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Affiliation(s)
- Zoe Bont
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | - Marc Pfander
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | | | - Meret Huber
- Institute of Plant Biology and Biotechnology, University of Münster, Münster, Germany
| | - Erik H Poelman
- Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands
| | - Ciska E Raaijmakers
- Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, The Netherlands
| | - Matthias Erb
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
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23
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Goldberg JK, Lively CM, Sternlieb SR, Pintel G, Hare JD, Morrissey MB, Delph LF. Herbivore-mediated negative frequency-dependent selection underlies a trichome dimorphism in nature. Evol Lett 2020; 4:83-90. [PMID: 32055414 PMCID: PMC7006469 DOI: 10.1002/evl3.157] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 12/12/2019] [Accepted: 12/19/2019] [Indexed: 02/06/2023] Open
Abstract
Negative frequency-dependent selection (NFDS) has been shown to maintain polymorphism in a diverse array of traits. The action of NFDS has been confirmed through modeling, experimental approaches, and genetic analyses. In this study, we investigated NFDS in the wild using morph-frequency changes spanning a 20-year period from over 30 dimorphic populations of Datura wrightii. In these populations, plants either possess glandular (sticky) or non-glandular (velvety) trichomes, and the ratio of these morphs varies substantially among populations. Our method provided evidence that NFDS, rather than drift or migration, is the primary force maintaining this dimorphism. Most populations that were initially dimorphic remained dimorphic, and the overall mean and variance in morph frequency did not change over time. Furthermore, morph-frequency differences were not related to geographic distances. Together, these results indicate that neither directional selection, drift, or migration played a substantial role in determining morph frequencies. However, as predicted by negative frequency-dependent selection, we found that the rare morph tended to increase in frequency, leading to a negative relationship between the change in the frequency of the sticky morph and its initial frequency. In addition, we found that morph-frequency change over time was significantly correlated with the damage inflicted by two herbivores: Lema daturaphila and Tupiochoris notatus. The latter is a specialist on the sticky morph and damage by this herbivore was greatest when the sticky morph was common. The reverse was true for L. daturaphila, such that damage increased with the frequency of the velvety morph. These findings suggest that these herbivores contribute to balancing selection on the observed trichome dimorphism.
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Affiliation(s)
- Jay K. Goldberg
- Department of BiologyIndiana UniversityBloomingtonIndiana47405
| | | | | | | | - J. Daniel Hare
- Department of EntomologyUniversity of CaliforniaRiversideCalifornia92521
| | | | - Lynda F. Delph
- Department of BiologyIndiana UniversityBloomingtonIndiana47405
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24
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Zhang X, van Doan C, Arce CCM, Hu L, Gruenig S, Parisod C, Hibbard BE, Hervé MR, Nielson C, Robert CAM, Machado RAR, Erb M. Plant defense resistance in natural enemies of a specialist insect herbivore. Proc Natl Acad Sci U S A 2019; 116:23174-81. [PMID: 31659056 DOI: 10.1073/pnas.1912599116] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Certain adapted insect herbivores utilize plant toxins for self-defense against their own enemies. These adaptations structure ecosystems and limit our capacity to use biological control agents to manage specialized agricultural pests. We show that entomopathogenic nematodes that are exposed to the western corn rootworm, an important agricultural pest that sequesters defense metabolites from maize, can evolve resistance to these defenses. Resisting the plant defense metabolites likely allows the nematodes to infect and kill the western corn rootworm more efficiently. These findings illustrate how predators can counter the plant-based resistance strategies of specialized insect herbivores. Breeding or engineering biological control agents that resist plant defense metabolites may improve their capacity to kill important agricultural pests such as the western corn rootworm. Plants defend themselves against herbivores through the production of toxic and deterrent metabolites. Adapted herbivores can tolerate and sometimes sequester these metabolites, allowing them to feed on defended plants and become toxic to their own enemies. Can herbivore natural enemies overcome sequestered plant defense metabolites to prey on adapted herbivores? To address this question, we studied how entomopathogenic nematodes cope with benzoxazinoid defense metabolites that are produced by grasses and sequestered by a specialist maize herbivore, the western corn rootworm. We find that nematodes from US maize fields in regions in which the western corn rootworm was present over the last 50 y are behaviorally and metabolically resistant to sequestered benzoxazinoids and more infective toward the western corn rootworm than nematodes from other parts of the world. Exposure of a benzoxazinoid-susceptible nematode strain to the western corn rootworm for 5 generations results in higher behavioral and metabolic resistance and benzoxazinoid-dependent infectivity toward the western corn rootworm. Thus, herbivores that are exposed to a plant defense sequestering herbivore can evolve both behavioral and metabolic resistance to plant defense metabolites, and these traits are associated with higher infectivity toward a defense sequestering herbivore. We conclude that plant defense metabolites that are transferred through adapted herbivores may result in the evolution of resistance in herbivore natural enemies. Our study also identifies plant defense resistance as a potential target for the improvement of biological control agents.
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25
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Chisholm PJ, Eigenbrode SD, Clark RE, Basu S, Crowder DW. Plant-mediated interactions between a vector and a non-vector herbivore promote the spread of a plant virus. Proc Biol Sci 2019; 286:20191383. [PMID: 31551062 DOI: 10.1098/rspb.2019.1383] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Herbivores that transmit plant pathogens often share hosts with non-vector herbivores. These co-occurring herbivores can affect vector fitness and behaviour through competition and by altering host plant quality. However, few studies have examined how such interactions may both directly and indirectly influence the spread of a plant pathogen. Here, we conducted field and greenhouse trials to assess whether a defoliating herbivore (Sitona lineatus) mediated the spread of a plant pathogen, Pea enation mosaic virus (PEMV), by affecting the fitness and behaviour of Acrythosiphon pisum, the PEMV vector. We observed higher rates of PEMV spread when infectious A. pisum individuals shared hosts with S. lineatus individuals. Using structural equation models, we showed that herbivory from S. lineatus increased A. pisum fitness, which stimulated vector movement and PEMV spread. Moreover, plant susceptibility to PEMV was indirectly enhanced by S. lineatus, which displaced A. pisum individuals to the most susceptible parts of the plant. Subsequent analyses of plant defence genes revealed considerable differences in plant phytohormones associated with anti-herbivore and anti-pathogen defence when S. lineatus was present. Given that vectors interact with non-vector herbivores in natural and managed ecosystems, characterizing how such interactions affect pathogens would greatly enhance our understanding of disease ecology.
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Affiliation(s)
- Paul J Chisholm
- Department of Entomology, Washington State University, Pullman, WA, USA
| | - Sanford D Eigenbrode
- Department of Entomology, Plant Pathology, and Nematology, University of Idaho, Moscow, ID, USA
| | - Robert E Clark
- Department of Entomology, Washington State University, Pullman, WA, USA
| | - Saumik Basu
- Department of Entomology, Washington State University, Pullman, WA, USA
| | - David W Crowder
- Department of Entomology, Washington State University, Pullman, WA, USA
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26
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Jack CN, Friesen ML. Rapid evolution of Medicago polymorpha during invasion shifts interactions with the soybean looper. Ecol Evol 2019; 9:10522-10533. [PMID: 31632647 PMCID: PMC6787872 DOI: 10.1002/ece3.5572] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/27/2019] [Accepted: 07/30/2019] [Indexed: 12/18/2022] Open
Abstract
The Enemy Release Hypothesis posits that invasion of novel habitats can be facilitated by the absence of coevolved herbivores. However, a new environment and interactions with unfamiliar herbivores may impose selection on invading plants for traits that reduce their attractiveness to herbivores or for enhanced defenses compared to native host plants, leading to a pattern similar to enemy release but driven by evolutionary change rather than ecological differences. The Shifting Defense Hypothesis posits that plants in novel habitats will shift from specialized defense mechanisms to defense mechanisms effective against generalist herbivores in the new range. We tested these ideas by comparing herbivore preference and performance of native (Eurasia)- and invasive (New World)-range Medicago polymorpha, using a generalist herbivore, the soybean looper, that co-occurs with M. polymorpha in its New World invaded range. We found that soybean loopers varied in preference and performance depending on host genotype and that overall the herbivore preferred to consume plant genotypes from naïve populations from Eurasia. This potentially suggests that range expansion of M. polymorpha into the New World has led to rapid evolution of a variety of traits that have helped multiple populations become established, including those that may allow invasive populations to resist herbivory. Thus, enemy release in a novel range can occur through rapid evolution by the plant during invasion, as predicted by the Shifting Defense Hypothesis, rather than via historical divergence.
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Affiliation(s)
- Chandra N. Jack
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan
- BEACON Center for the Study of Evolution in ActionEast LansingMichigan
- Department of Plant PathologyWashington State UniversityPullmanWashington
| | - Maren L. Friesen
- Department of Plant BiologyMichigan State UniversityEast LansingMichigan
- BEACON Center for the Study of Evolution in ActionEast LansingMichigan
- Department of Plant PathologyWashington State UniversityPullmanWashington
- Department of Crop and Soil SciencesWashington State UniversityPullmanWashington
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27
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Nordkvist M, Klapwijk MJ, Edenius L, Gershenzon J, Schmidt A, Björkman C. Trait-mediated indirect interactions: Moose browsing increases sawfly fecundity through plant-induced responses. Ecol Evol 2019; 9:10615-10629. [PMID: 31624570 PMCID: PMC6787786 DOI: 10.1002/ece3.5581] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/10/2019] [Accepted: 07/26/2019] [Indexed: 11/29/2022] Open
Abstract
Induced responses in plants, initiated by herbivory, create potential for trait-mediated indirect interactions among herbivores. Responses to an initial herbivore may change a number of plant traits that subsequently alter ecological processes with additional herbivores. Although common, indirect interactions between taxonomically distant herbivores, such as mammals and insects, are less studied than between taxonomically related species (i.e., insect-insect). In terms of mammal-insect interactions, effects on insect numbers (e.g., density) are relatively well studied, whereas effects on performance (e.g., fecundity) are rarely explored. Moreover, few studies have explored mammal-insect interactions on coniferous plants.The aim of this study was to investigate the effect of mammalian induced responses on insect performance. We specifically investigated the effect of moose (Alces alces) browsing on Scots pine (Pinus sylvestris) and subsequent effects on sawfly (Neodiprion sertifer) performance.Sawfly larvae were reared on browsed, clipped, and unbrowsed control pine trees in a controlled field experiment. Afterward, cocoon weight was measured. Needle C:N ratio and di-terpene content were measured in response to browsing.Sawfly performance was enhanced on trees browsed by moose. Cocoon weight (proxy for fecundity) was 9 and 13% higher on browsed and clipped trees compared to unbrowsed trees. Cocoon weight was weakly related to needle C:N ratio, and browsed trees had lower a C:N ratio compared to unbrowsed trees. Needle di-terpene content, known to affect sawfly performance, was neither affected by the browsing treatments nor did it correlate with sawfly weight.We conclude that mammalian herbivory can affect insect herbivore performance, with potential consequences for ecological communities and with particular importance for insect population dynamics. The measured plant variables could not fully explain the effect on sawfly performance providing a starting point for the consideration of additional plant responses induced by mammalian browsing affecting insect performance.
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Affiliation(s)
- Michelle Nordkvist
- Department of EcologySwedish University of Agricultural SciencesUppsalaSweden
| | - Maartje J. Klapwijk
- Department of EcologySwedish University of Agricultural SciencesUppsalaSweden
| | - Lars Edenius
- Department of Wildlife, Fish, and Environmental StudiesSwedish University of Agricultural SciencesUmeåSweden
| | - Jonathan Gershenzon
- Department of BiochemistryMax Planck Institute for Chemical EcologyJenaGermany
| | - Axel Schmidt
- Department of BiochemistryMax Planck Institute for Chemical EcologyJenaGermany
| | - Christer Björkman
- Department of EcologySwedish University of Agricultural SciencesUppsalaSweden
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28
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Field E, Schönrogge K, Barsoum N, Hector A, Gibbs M. Individual tree traits shape insect and disease damage on oak in a climate-matching tree diversity experiment. Ecol Evol 2019; 9:8524-8540. [PMID: 31410259 PMCID: PMC6686283 DOI: 10.1002/ece3.5357] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 05/04/2019] [Indexed: 11/09/2022] Open
Abstract
Diversifying planted forests by increasing genetic and species diversity is often promoted as a method to improve forest resilience to climate change and reduce pest and pathogen damage. In this study, we used a young tree diversity experiment replicated at two sites in the UK to study the impacts of tree diversity and tree provenance (geographic origin) on the oak (Quercus robur) insect herbivore community and a specialist biotrophic pathogen, oak powdery mildew. Local UK, French, and Italian provenances were planted in monocultures, provenance mixtures, and species mixes, allowing us to test whether: (a) local and nonlocal provenances differ in their insect herbivore and pathogen communities, and (b) admixing trees leads to associational effects on insect herbivore and pathogen damage. Tree diversity had variable impacts on foliar organisms across sites and years, suggesting that diversity effects can be highly dependent on environmental context. Provenance identity impacted upon both herbivores and powdery mildew, but we did not find consistent support for the local adaptation hypothesis for any group of organisms studied. Independent of provenance, we found tree vigor traits (shoot length, tree height) and tree apparency (the height of focal trees relative to their surroundings) were consistent positive predictors of powdery mildew and insect herbivory. Synthesis. Our results have implications for understanding the complex interplay between tree identity and diversity in determining pest damage, and show that tree traits, partially influenced by tree genotype, can be important drivers of tree pest and pathogen loads.
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Affiliation(s)
- Elsa Field
- Department of Plant SciencesUniversity of OxfordOxfordUK
| | | | | | - Andrew Hector
- Department of Plant SciencesUniversity of OxfordOxfordUK
| | - Melanie Gibbs
- Centre for Ecology & HydrologyCrowmarsh GiffordWallingfordUK
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29
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Firn J, Nguyen H, Schütz M, Risch AC. Leaf trait variability between and within subalpine grassland species differs depending on site conditions and herbivory. Proc Biol Sci 2019; 286:20190429. [PMID: 31337314 DOI: 10.1098/rspb.2019.0429] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Plant traits are commonly used to predict ecosystem-level processes, but the validity of such predictions is dependent on the assumption that trait variability between species is greater than trait variability within a species-the robustness assumption. Here, we compare leaf trait intraspecific and interspecific variability depending on geographical differences between sites and 5 years of experimental herbivore exclusion in two vegetation types of subalpine grasslands in Switzerland. Four leaf traits were measured from eight herbaceous species common to all 18 sites. Intraspecific trait variability differed significantly depending on site and herbivory. However, the amount and structure of variability depended on the trait measured and whether considering leaf traits separately or multiple leaf traits simultaneously. Leaf phosphorus concentration showed the highest intraspecific variability, while specific leaf area showed the highest interspecific variability and displayed intraspecific variability only in response to herbivore exclusion. Species identity based on multiple traits was not predictable. We find intraspecific variability is an essential consideration when using plant functional traits as a common currency not just species mean traits. This is particularly true for leaf nutrient concentrations, which showed high intraspecific variability in response to site differences and herbivore exclusion, a finding which suggests that the robustness assumption does not always hold.
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Affiliation(s)
- Jennifer Firn
- School of Earth, Environmental and Biological Sciences, Queensland University of Technology (QUT), Brisbane, Queensland 4001, Australia
| | - Huong Nguyen
- School of Earth, Environmental and Biological Sciences, Queensland University of Technology (QUT), Brisbane, Queensland 4001, Australia
| | - Martin Schütz
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
| | - Anita C Risch
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zürcherstrasse 111, 8903 Birmensdorf, Switzerland
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30
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Deslauriers A, Fournier MP, Cartenì F, Mackay J. Phenological shifts in conifer species stressed by spruce budworm defoliation. Tree Physiol 2019; 39:590-605. [PMID: 30597102 DOI: 10.1093/treephys/tpy135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/31/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
Synchrony between host budburst and insect emergence greatly influences the time window for insect development and survival. A few alterations of bud phenology have been reported under defoliation without clear consensus regarding the direction of effects, i.e., advance or delay. Here, we compared budburst phenology between conifers in defoliation and control treatments, and measured carbon allocation as a potential mechanistic explanation of changes in phenology. In a 2-year greenhouse experiment, saplings of balsam fir, black spruce and white spruce of two different provenances (north and south) were subjected to either control (no larvae) or natural defoliation treatment (larvae added) by spruce budworm. Bud and instar phenology, primary and secondary growth, defoliation and non-structural carbohydrates were studied during the growing season. No differences were observed in bud phenology during the first year of defoliation. After 1 year of defoliation, bud phenology advanced by 6-7 days in black spruce and balsam fir and by 3.5 days in white spruce compared with the control. Because of this earlier bud break, apical and shoot growth exceeded 50% of its final length before mature instar defoliation occurred, which decreased the overall level of damage. A sugar-mediated response, via earlier starch breakdown, and higher sugar availability to buds explains the advanced budburst in defoliated saplings. The advanced phenological response to defoliation was consistent across the conifer species and provenances except for one species × provenance combination. Allocation of carbon to buds and shoots growth at the expense of wood growth in the stem and reserve accumulation represents a shift in the physiological resources priorities to ensure tree survival. This advancement in bud phenology could be considered as a physiological response to defoliation based on carbohydrate needs for primary growth, rather than a resistance trait to spruce budworm.
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Affiliation(s)
- Annie Deslauriers
- Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 Boulevard de l'Université, Chicoutimi, QC, Canada
| | - Marie-Pier Fournier
- Département des Sciences Fondamentales, Université du Québec à Chicoutimi, 555 Boulevard de l'Université, Chicoutimi, QC, Canada
| | - Fabrizio Cartenì
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, Portici (NA), Italy
| | - John Mackay
- Centre d'Étude de la Forêt, Département des Sciences du Bois et de la Forêt, Université Laval, Québec, QC, Canada
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada
- Department of Plant Sciences, University of Oxford, Oxford, UK
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Muola A, Stenberg JA. Folivory has long-term effects on sexual but not on asexual reproduction in woodland strawberry. Ecol Evol 2018; 8:12250-12259. [PMID: 30598815 PMCID: PMC6303713 DOI: 10.1002/ece3.4687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 09/03/2018] [Accepted: 09/19/2018] [Indexed: 11/07/2022] Open
Abstract
Plant fitness is often a result of both sexual and asexual reproductive success and, in perennial plants, over several years. Folivory can affect both modes of reproduction. However, little is known about the effects of folivory on resource allocation to the two modes of reproduction simultaneously and across years. In a 2-year common garden experiment, we examined the effects of different levels of folivory by the strawberry leaf beetle, Galerucella tenella, on current growth, as well as current and future sexual and asexual reproduction (runners) of perennial woodland strawberry, Fragaria vesca. In addition, we measured the chlorophyll content in leaves in the year of experimental damage to determine whether there was increased photosynthetic activity, and, thus, a compensatory response to herbivory. Finally, we tested whether the previous year's folivory, as a result of its effect on plant fitness, affected the level of natural herbivory the plant experienced during the subsequent year. In the year of experimental damage, plants that were exposed to moderate and high levels of folivory (25% and 50% leaf area consumed, respectively) increased their photosynthetic activity compared to control plants. However, only plants exposed to high folivory exhibited negative effects, with a lower probability of flowering compared to control plants, indicating that plants exposed to low or moderate folivory were able to compensate for the damage. Negative effects of folivory were carried over to the subsequent year. Plants that were exposed to moderate folivory (25% leaf area consumed) during first year produced fewer flowers and fruits in the subsequent year. Runner production was consistently unaffected by folivory. The effects of experimental folivory on the level of natural herbivory were mediated via its effects on plant fitness. Our results show that the negative effects of folivory only influence sexual reproduction in woodland strawberry. Furthermore, even though woodland strawberry can tolerate moderate amounts of folivory in the short term, the negative effects on fitness appear later; this highlights the importance of studying the effects of herbivory over consecutive years in perennial plants.
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Affiliation(s)
- Anne Muola
- Department of Plant Protection BiologySwedish University of Agricultural SciencesAlnarpSweden
- Section of Ecology, Department of BiologyUniversity of TurkuTurkuFinland
| | - Johan A. Stenberg
- Department of Plant Protection BiologySwedish University of Agricultural SciencesAlnarpSweden
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de Vries J, Poelman EH, Anten N, Evers JB. Elucidating the interaction between light competition and herbivore feeding patterns using functional-structural plant modelling. Ann Bot 2018; 121:1019-1031. [PMID: 29373660 PMCID: PMC5906910 DOI: 10.1093/aob/mcx212] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/11/2018] [Indexed: 05/22/2023]
Abstract
Background and Aims Plants usually compete with neighbouring plants for resources such as light as well as defend themselves against herbivorous insects. This requires investment of limiting resources, resulting in optimal resource distribution patterns and trade-offs between growth- and defence-related traits. A plant's competitive success is determined by the spatial distribution of its resources in the canopy. The spatial distribution of herbivory in the canopy in turn differs between herbivore species as the level of herbivore specialization determines their response to the distribution of resources and defences in the canopy. Here, we investigated to what extent competition for light affects plant susceptibility to herbivores with different feeding preferences. Methods To quantify interactions between herbivory and competition, we developed and evaluated a 3-D spatially explicit functional-structural plant model for Brassica nigra that mechanistically simulates competition in a dynamic light environment, and also explicitly models leaf area removal by herbivores with different feeding preferences. With this novel approach, we can quantitatively explore the extent to which herbivore feeding location and light competition interact in their effect on plant performance. Key Results Our results indicate that there is indeed a strong interaction between levels of plant-plant competition and herbivore feeding preference. When plants did not compete, herbivory had relatively small effects irrespective of feeding preference. Conversely, when plants competed, herbivores with a preference for young leaves had a strong negative effect on the competitiveness and subsequent performance of the plant, whereas herbivores with a preference for old leaves did not. Conclusions Our study predicts how plant susceptibility to herbivory depends on the composition of the herbivore community and the level of plant competition, and highlights the importance of considering the full range of dynamics in plant-plant-herbivore interactions.
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Affiliation(s)
- Jorad de Vries
- Wageningen University, Laboratory of Entomology, Wageningen, The Netherlands
- Wageningen University, Centre for Crop System Analysis, Wageningen, The Netherlands
| | - Erik H Poelman
- Wageningen University, Laboratory of Entomology, Wageningen, The Netherlands
| | - Niels Anten
- Wageningen University, Centre for Crop System Analysis, Wageningen, The Netherlands
| | - Jochem B Evers
- Wageningen University, Centre for Crop System Analysis, Wageningen, The Netherlands
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Abstract
Many morphological and chemical features of plants are classified as plant defenses against herbivores. By definition, plant defenses should increase a plant's fitness (i.e., its contribution to the gene pool of the next generation) as a function of herbivory. Over the past years, substantial progress has been made in understanding and manipulating the mechanistic basis of many putative plant defense traits. However, most plant defenses are still characterized by proximate variables such as herbivore performance or plant damage rather than actual fitness. Determining fitness benefits as a function of herbivory therefore remains a major knowledge gap that must be filled to understand the ecology and evolution of plant defenses.
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Affiliation(s)
- Matthias Erb
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
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34
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Nunes KA, Kotanen PM. Comparative impacts of aboveground and belowground enemies on an invasive thistle. Ecol Evol 2018; 8:1430-1440. [PMID: 29435222 PMCID: PMC5792520 DOI: 10.1002/ece3.3751] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/04/2017] [Accepted: 11/26/2017] [Indexed: 11/17/2022] Open
Abstract
Most research examining how herbivores and pathogens affect performance of invasive plants focuses on aboveground interactions. Although important, the role of belowground communities remains poorly understood, and the relative impact of aboveground and belowground interactions is still debated. As well, most studies of belowground interactions have been carried out in controlled environments, so little is known about the role of these interactions under natural conditions or how these relationships may change across a plant's range. Using the invasive plant Cirsium arvense, we performed a reciprocal transplant experiment to test the relative impacts of above- and belowground interactions at three sites across a 509-km latitudinal gradient in its invaded range in Ontario, Canada. At each site, C. arvense seedlings were protected with above- and/or belowground exclosures in a factorial design. Plant performance (biomass, height, stem thickness, number of leaves, length of longest leaf, maximum rhizome length) was greatest when both above- and belowground exclosures were applied and lowest when no exclosures were applied. When only one type of exclosure was applied, biomass generally improved more with belowground exclosures than with aboveground exclosures. Despite site-to-site differences in foliar damage, root damage, and mesofaunal populations, belowground interactions generally had a greater negative impact on performance than aboveground herbivory alone. These results stress the importance of including both aboveground enemy interactions and plant-soil interactions in studies of plant community dynamics and invader performance.
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Affiliation(s)
- Krystal A. Nunes
- Department of Ecology and Evolutionary BiologyUniversity of Toronto MississaugaMississaugaONCanada
| | - Peter M. Kotanen
- Department of Ecology and Evolutionary BiologyUniversity of Toronto MississaugaMississaugaONCanada
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35
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Liu M, Zhou F, Pan X, Zhang Z, Traw MB, Li B. Specificity of herbivore-induced responses in an invasive species, Alternanthera philoxeroides (alligator weed). Ecol Evol 2017; 8:59-70. [PMID: 29321851 PMCID: PMC5756832 DOI: 10.1002/ece3.3615] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 10/03/2017] [Accepted: 10/11/2017] [Indexed: 11/26/2022] Open
Abstract
Herbivory‐induced responses in plants can both negatively affect subsequently colonizing herbivores and mitigate the effect of herbivory on the host. However, it is still less known whether plants exhibit specific responses to specialist and generalist herbivores in non‐secondary metabolite traits and how specificity to specialists and generalists differs between invasive and native plant populations. We exposed an invasive plant, Alternanthera philoxeroides, to Agasicles hygrophila (Coleoptera, Chrysomelidae; specialist), Spodoptera litura (Lepidoptera, Noctuidae; generalist), manual clipping, or application of exogenous jasmonic acid and examined both the specificity of elicitation in traits of fitness (e.g., aboveground biomass), morphology (e.g., root:shoot ratio), and chemistry (e.g., C/N ratio and lignin), and specificity of effect on the subsequent performance of A. hygrophila and S. litura. Then, we assessed variation of the specificity between invasive and native populations (USA and Argentina, respectively). The results showed S. litura induced higher branching intensity and specific leaf area but lower C/N ratio than A. hygrophila, whereas A. hygrophila induced higher trichome density than S. litura. The negative effect of induction on subsequent larval growth was greater for S. litura than for A. hygrophila. Invasive populations had a weaker response to S. litura than to A. hygrophila in triterpenoid saponins and C/N ratio, while native populations responded similarly to these two herbivores. The specific effect on the two herbivores feeding on induced plants did not vary between invasive and native populations. Overall, we demonstrate specificity of elicitation to specialist and generalist herbivores in non‐secondary metabolite traits, and that the generalist is more susceptible to induction than the specialist. Furthermore, chemical responses specific to specialist and generalist herbivores only exist in the invasive populations, consistent with an evolutionary change in specificity in the invasive populations.
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Affiliation(s)
- Mu Liu
- Institute of Biodiversity Science Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Fudan University Shanghai China
| | - Fang Zhou
- Institute of Biodiversity Science Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Fudan University Shanghai China
| | - Xiaoyun Pan
- Institute of Biodiversity Science Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Fudan University Shanghai China
| | - Zhijie Zhang
- Institute of Biodiversity Science Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Fudan University Shanghai China
| | | | - Bo Li
- Institute of Biodiversity Science Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering Fudan University Shanghai China
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36
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O'Brien MJ, Brezzi M, Schuldt A, Zhang J, Ma K, Schmid B, Niklaus PA. Tree diversity drives diversity of arthropod herbivores, but successional stage mediates detritivores. Ecol Evol 2017; 7:8753-8760. [PMID: 29152174 PMCID: PMC5677472 DOI: 10.1002/ece3.3411] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 07/28/2017] [Accepted: 08/03/2017] [Indexed: 11/06/2022] Open
Abstract
The high tree diversity of subtropical forests is linked to the biodiversity of other trophic levels. Disentangling the effects of tree species richness and composition, forest age, and stand structure on higher trophic levels in a forest landscape is important for understanding the factors that promote biodiversity and ecosystem functioning. Using a plot network spanning gradients of tree diversity and secondary succession in subtropical forest, we tested the effects of tree community characteristics (species richness and composition) and forest succession (stand age) on arthropod community characteristics (morphotype diversity, abundance and composition) of four arthropod functional groups. We posit that these gradients differentially affect the arthropod functional groups, which mediates the diversity, composition, and abundance of arthropods in subtropical forests. We found that herbivore richness was positively related to tree species richness. Furthermore, the composition of herbivore communities was associated with tree species composition. In contrast, detritivore richness and composition was associated with stand age instead of tree diversity. Predator and pollinator richness and abundance were not strongly related to either gradient, although positive trends with tree species richness were found for predators. The weaker effect of tree diversity on predators suggests a cascading diversity effect from trees to herbivores to predators. Our results suggest that arthropod diversity in a subtropical forest reflects the net outcome of complex interactions among variables associated with tree diversity and stand age. Despite this complexity, there are clear linkages between the overall richness and composition of tree and arthropod communities, in particular herbivores, demonstrating that these trophic levels directly impact each other.
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Affiliation(s)
- Michael J. O'Brien
- Estación Experimental de Zonas ÁridasConsejo Superior de Investigaciones CientíficasAlmeríaSpain
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Matteo Brezzi
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
- Institute of Global HealthUniversity of GenevaGenevaSwitzerland
| | - Andreas Schuldt
- German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐LeipzigLeipzigGermany
| | - Jia‐Yong Zhang
- Institute of EcologyZhejiang Normal UniversityJinhuaZhejiang ProvinceChina
| | - Keping Ma
- State Key Laboratory of Vegetation and Environmental ChangeInstitute of BotanyChinese Academy of SciencesBeijingChina
| | - Bernhard Schmid
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
| | - Pascal A. Niklaus
- Department of Evolutionary Biology and Environmental StudiesUniversity of ZurichZurichSwitzerland
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37
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Vowles T, Gunnarsson B, Molau U, Hickler T, Klemedtsson L, Björk RG. Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range. J Ecol 2017; 105:1547-1561. [PMID: 29200500 PMCID: PMC5697633 DOI: 10.1111/1365-2745.12753] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 01/12/2017] [Indexed: 06/02/2023]
Abstract
One of the most palpable effects of warming in Arctic ecosystems is shrub expansion above the tree line. However, previous studies have found that reindeer can influence plant community responses to warming and inhibit shrubification of the tundra.We revisited grazed (ambient) and ungrazed study plots (exclosures), at the southern as well as the northern limits of the Swedish alpine region, to study long-term grazing effects and vegetation changes in response to increasing temperatures between 1995 and 2011, in two vegetation types (shrub heath and mountain birch forest).In the field layer at the shrub heath sites, evergreen dwarf shrubs had increased in cover from 26% to 49% but were unaffected by grazing. Deciduous dwarf and tall shrubs also showed significant, though smaller, increases over time. At the birch forest sites, the increase was similar for evergreen dwarf shrubs (20-48%) but deciduous tall shrubs did not show the same consistent increase over time as in the shrub heath.The cover and height of the shrub layer were significantly greater in exclosures at the shrub heath sites, but no significant treatment effects were found on species richness or diversity.July soil temperatures and growing season thawing degree days (TDD) were higher in exclosures at all but one site, and there was a significant negative correlation between mean shrub layer height and soil TDD at the shrub heath sites. Synthesis. This study shows that shrub expansion is occurring rapidly in the Scandes mountain range, both above and below the tree line. Tall, deciduous shrubs had benefitted significantly from grazing exclosure, both in terms of cover and height, which in turn lowered summer soil temperatures. However, the overriding vegetation shift across our sites was the striking increase in evergreen dwarf shrubs, which were not influenced by grazing. As the effects of an increase in evergreen dwarf shrubs and more recalcitrant plant litter may to some degree counteract some of the effects of an increase in deciduous tall shrubs, herbivore influence on shrub interactions is potentially of great importance for shaping arctic shrub expansion and its associated ecosystem effects.
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Affiliation(s)
- Tage Vowles
- Department of Biological and Environmental SciencesUniversity of GothenburgBox 46140530GöteborgSweden
| | - Bengt Gunnarsson
- Department of Biological and Environmental SciencesUniversity of GothenburgBox 46140530GöteborgSweden
| | - Ulf Molau
- Department of Biological and Environmental SciencesUniversity of GothenburgBox 46140530GöteborgSweden
| | - Thomas Hickler
- Senckenberg Biodiversity & Climate Research Centre Bik FSenckenberganalge 25D‐60325FrankfurtGermany
- Department of Physical GeographyGoethe University FrankfurtAltenhöferallee 1D‐60438FrankfurtGermany
| | - Leif Klemedtsson
- Department of Earth SciencesUniversity of GothenburgBox 46040530GöteborgSweden
| | - Robert G. Björk
- Department of Earth SciencesUniversity of GothenburgBox 46040530GöteborgSweden
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38
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Wilschut RA, Silva JCP, Garbeva P, van der Putten WH. Belowground Plant-Herbivore Interactions Vary among Climate-Driven Range-Expanding Plant Species with Different Degrees of Novel Chemistry. Front Plant Sci 2017; 8:1861. [PMID: 29118781 PMCID: PMC5660973 DOI: 10.3389/fpls.2017.01861] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 10/11/2017] [Indexed: 05/06/2023]
Abstract
An increasing number of studies report plant range expansions to higher latitudes and altitudes in response to global warming. However, consequences for interactions with other species in the novel ranges are poorly understood. Here, we examine how range-expanding plant species interact with root-feeding nematodes from the new range. Root-feeding nematodes are ubiquitous belowground herbivores that may impact the structure and composition of natural vegetation. Because of their ecological novelty, we hypothesized that range-expanding plant species will be less suitable hosts for root-feeding nematodes than native congeneric plant species. In greenhouse and lab trials we compared nematode preference and performance of two root-feeding nematode species between range-expanding plant species and their congeneric natives. In order to understand differences in nematode preferences, we compared root volatile profiles of all range-expanders and congeneric natives. Nematode preferences and performances differed substantially among the pairs of range-expanders and natives. The range-expander that had the most unique volatile profile compared to its related native was unattractive and a poor host for nematodes. Other range-expanding plant species that differed less in root chemistry from native congeners, also differed less in nematode attraction and performance. We conclude that the three climate-driven range-expanding plant species studied varied considerably in their chemical novelty compared to their congeneric natives, and therefore affected native root-feeding nematodes in species-specific ways. Our data suggest that through variation in chemical novelty, range-expanding plant species may vary in their impacts on belowground herbivores in the new range.
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Affiliation(s)
- Rutger A. Wilschut
- Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
| | - Julio C. P. Silva
- Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
| | - Paolina Garbeva
- Department of Microbial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
| | - Wim H. van der Putten
- Department of Terrestrial Ecology, Netherlands Institute of Ecology, Wageningen, Netherlands
- Laboratory of Nematology, Wageningen University and Research, Wageningen, Netherlands
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Endara MJ, Coley PD, Ghabash G, Nicholls JA, Dexter KG, Donoso DA, Stone GN, Pennington RT, Kursar TA. Coevolutionary arms race versus host defense chase in a tropical herbivore-plant system. Proc Natl Acad Sci U S A 2017; 114:E7499-505. [PMID: 28827317 DOI: 10.1073/pnas.1707727114] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Coevolutionary models suggest that herbivores drive diversification and community composition in plants. For herbivores, many questions remain regarding how plant defenses shape host choice and community structure. We addressed these questions using the tree genus Inga and its lepidopteran herbivores in the Amazon. We constructed phylogenies for both plants and insects and quantified host associations and plant defenses. We found that similarity in herbivore assemblages between Inga species was correlated with similarity in defenses. There was no correlation with phylogeny, a result consistent with our observations that the expression of defenses in Inga is independent of phylogeny. Furthermore, host defensive traits explained 40% of herbivore community similarity. Analyses at finer taxonomic scales showed that different lepidopteran clades select hosts based on different defenses, suggesting taxon-specific histories of herbivore-host plant interactions. Finally, we compared the phylogeny and defenses of Inga to phylogenies for the major lepidopteran clades. We found that closely related herbivores fed on Inga with similar defenses rather than on closely related plants. Together, these results suggest that plant defenses might be more evolutionarily labile than the herbivore traits related to host association. Hence, there is an apparent asymmetry in the evolutionary interactions between Inga and its herbivores. Although plants may evolve under selection by herbivores, we hypothesize that herbivores may not show coevolutionary adaptations, but instead "chase" hosts based on the herbivore's own traits at the time that they encounter a new host, a pattern more consistent with resource tracking than with the arms race model of coevolution.
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40
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Schuldt A, Hönig L, Li Y, Fichtner A, Härdtle W, von Oheimb G, Welk E, Bruelheide H. Herbivore and pathogen effects on tree growth are additive, but mediated by tree diversity and plant traits. Ecol Evol 2017; 7:7462-7474. [PMID: 28944031 PMCID: PMC5606881 DOI: 10.1002/ece3.3292] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 07/03/2017] [Accepted: 07/09/2017] [Indexed: 01/06/2023] Open
Abstract
Herbivores and fungal pathogens are key drivers of plant community composition and functioning. The effects of herbivores and pathogens are mediated by the diversity and functional characteristics of their host plants. However, the combined effects of herbivory and pathogen damage, and their consequences for plant performance, have not yet been addressed in the context of biodiversity–ecosystem functioning research. We analyzed the relationships between herbivory, fungal pathogen damage and their effects on tree growth in a large‐scale forest‐biodiversity experiment. Moreover, we tested whether variation in leaf trait and climatic niche characteristics among tree species influenced these relationships. We found significant positive effects of herbivory on pathogen damage, and vice versa. These effects were attenuated by tree species richness—because herbivory increased and pathogen damage decreased with increasing richness—and were most pronounced for species with soft leaves and narrow climatic niches. However, herbivory and pathogens had contrasting, independent effects on tree growth, with pathogens decreasing and herbivory increasing growth. The positive herbivory effects indicate that trees might be able to (over‐)compensate for local damage at the level of the whole tree. Nevertheless, we found a dependence of these effects on richness, leaf traits and climatic niche characteristics of the tree species. This could mean that the ability for compensation is influenced by both biodiversity loss and tree species identity—including effects of larger‐scale climatic adaptations that have been rarely considered in this context. Our results suggest that herbivory and pathogens have additive but contrasting effects on tree growth. Considering effects of both herbivory and pathogens may thus help to better understand the net effects of damage on tree performance in communities differing in diversity. Moreover, our study shows how species richness and species characteristics (leaf traits and climatic niches) can modify tree growth responses to leaf damage under real‐world conditions.
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Affiliation(s)
- Andreas Schuldt
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.,Institute of Biology/Geobotany and Botanical Garden Martin-Luther-University Halle-Wittenberg Halle Germany
| | - Lydia Hönig
- Institute of Biology/Geobotany and Botanical Garden Martin-Luther-University Halle-Wittenberg Halle Germany
| | - Ying Li
- Institute of Ecology Leuphana University Lüneburg Lüneburg Germany
| | - Andreas Fichtner
- Institute of Ecology Leuphana University Lüneburg Lüneburg Germany
| | - Werner Härdtle
- Institute of Ecology Leuphana University Lüneburg Lüneburg Germany
| | - Goddert von Oheimb
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.,Institute of General Ecology and Environmental Protection Technische Universität Dresden Tharandt Germany
| | - Erik Welk
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.,Institute of Biology/Geobotany and Botanical Garden Martin-Luther-University Halle-Wittenberg Halle Germany
| | - Helge Bruelheide
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Leipzig Germany.,Institute of Biology/Geobotany and Botanical Garden Martin-Luther-University Halle-Wittenberg Halle Germany
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Ohse B, Seele C, Holzwarth F, Wirth C. Different facets of tree sapling diversity influence browsing intensity by deer dependent on spatial scale. Ecol Evol 2017; 7:6779-6789. [PMID: 28904759 PMCID: PMC5587474 DOI: 10.1002/ece3.3217] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/02/2017] [Accepted: 06/06/2017] [Indexed: 11/11/2022] Open
Abstract
Browsing of tree saplings by deer hampers forest regeneration in mixed forests across Europe and North America. It is well known that tree species are differentially affected by deer browsing, but little is known about how different facets of diversity, such as species richness, identity, and composition, affect browsing intensity at different spatial scales. Using forest inventory data from the Hainich National Park, a mixed deciduous forest in central Germany, we applied a hierarchical approach to model the browsing probability of patches (regional scale) as well as the species‐specific proportion of saplings browsed within patches (patch scale). We found that, at the regional scale, the probability that a patch was browsed increased with certain species composition, namely with low abundance of European beech (Fagus sylvatica L.) and high abundance of European ash (Fraxinus excelsior L.), whereas at the patch scale, the proportion of saplings browsed per species was mainly determined by the species’ identity, providing a “preference ranking” of the 11 tree species under study. Interestingly, at the regional scale, species‐rich patches were more likely to be browsed; however, at the patch scale, species‐rich patches showed a lower proportion of saplings per species browsed. Presumably, diverse patches attract deer, but satisfy nutritional needs faster, such that fewer saplings need to be browsed. Some forest stand parameters, such as more open canopies, increased the browsing intensity at either scale. By showing the effects that various facets of diversity, as well as environmental parameters, exerted on browsing intensity at the regional as well as patch scale, our study advances the understanding of mammalian herbivore–plant interactions across scales. Our results also indicate which regeneration patches and species are (least) prone to browsing and show the importance of different facets of diversity for the prediction and management of browsing intensity and regeneration dynamics.
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Affiliation(s)
- Bettina Ohse
- Institute of Systematic Botany and Functional Biodiversity Leipzig University Leipzig Germany
| | - Carolin Seele
- Institute of Systematic Botany and Functional Biodiversity Leipzig University Leipzig Germany
| | - Frédéric Holzwarth
- Institute of Systematic Botany and Functional Biodiversity Leipzig University Leipzig Germany
| | - Christian Wirth
- Institute of Systematic Botany and Functional Biodiversity Leipzig University Leipzig Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig Germany
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42
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Rhodes AC, Anderson V, St Clair SB. Ungulate herbivory alters leaf functional traits and recruitment of regenerating aspen. Tree Physiol 2017; 37:402-413. [PMID: 28338915 DOI: 10.1093/treephys/tpx015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 01/24/2017] [Indexed: 06/06/2023]
Abstract
Herbivory by ungulates can affect forest regeneration success, but its long-term impacts on tree function and recruitment are less studied. We evaluated strategies of resistance, tolerance and vertical escape against ungulate herbivory by evaluating leaf traits (photosynthesis, morphology and chemistry) and growth rates of aspen in the presence and absence of ungulate herbivores 1, 2, 3 and 26 years after fires initiated aspen suckering. Over the initial 3-year period, ~60% of aspen stems in unfenced plots showed evidence of being browsed by ungulates. After 3 years, aspen in unfenced plots had smaller leaves, were 50% shorter, and had 33% lower nonstructural carbohydrate concentrations and 33% greater concentrations of condensed tannins, when compared with fenced aspen. Aspen exposed to ungulate herbivory over a 26-year period maintained smaller leaves, had lower annual radial growth rates and were still below the critical height threshold of 2 m required to escape ungulate herbivory for successful recruitment. In contrast, the average height of aspen protected from ungulates was approaching 6 m. Over the 26-year period leaves in unfenced plots had 41% lower nonstructural carbohydrate concentrations and greater expression of defense compounds-condensed tannins (63%) and phenolic glycosides (102%)-than leaves in fenced plots. Photosynthetic rates were slightly higher in aspen that experienced ungulate browsing, suggesting that changes in leaf anatomy and chemistry due to ungulate herbivory did not interfere with photosynthesis. Our data suggest that ungulate browsing increases investment in chemical defense, lowers nonstructural carbohydrate concentrations and reduces leaf area, which decreases the recruitment potential of regenerating aspen.
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Affiliation(s)
- Aaron C Rhodes
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Val Anderson
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT 84602, USA
| | - Samuel B St Clair
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, UT 84602, USA
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Vergés A, Doropoulos C, Malcolm HA, Skye M, Garcia-Pizá M, Marzinelli EM, Campbell AH, Ballesteros E, Hoey AS, Vila-Concejo A, Bozec YM, Steinberg PD. Long-term empirical evidence of ocean warming leading to tropicalization of fish communities, increased herbivory, and loss of kelp. Proc Natl Acad Sci U S A 2016; 113:13791-13796. [PMID: 27849585 PMCID: PMC5137712 DOI: 10.1073/pnas.1610725113] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Some of the most profound effects of climate change on ecological communities are due to alterations in species interactions rather than direct physiological effects of changing environmental conditions. Empirical evidence of historical changes in species interactions within climate-impacted communities is, however, rare and difficult to obtain. Here, we demonstrate the recent disappearance of key habitat-forming kelp forests from a warming tropical-temperate transition zone in eastern Australia. Using a 10-y video dataset encompassing a 0.6 °C warming period, we show how herbivory increased as kelp gradually declined and then disappeared. Concurrently, fish communities from sites where kelp was originally abundant but subsequently disappeared became increasingly dominated by tropical herbivores. Feeding assays identified two key tropical/subtropical herbivores that consumed transplanted kelp within hours at these sites. There was also a distinct increase in the abundance of fishes that consume epilithic algae, and much higher bite rates by this group at sites without kelp, suggesting a key role for these fishes in maintaining reefs in kelp-free states by removing kelp recruits. Changes in kelp abundance showed no direct relationship to seawater temperatures over the decade and were also unrelated to other measured abiotic factors (nutrients and storms). Our results show that warming-mediated increases in fish herbivory pose a significant threat to kelp-dominated ecosystems in Australia and, potentially, globally.
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Affiliation(s)
- Adriana Vergés
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia;
- Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
| | - Christopher Doropoulos
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Commonwealth Scientific and Industrial Research Organization Oceans and Atmosphere, Dutton Park, QLD 4102, Australia
- Marine Spatial Ecology Lab, Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Hamish A Malcolm
- Marine Ecosystem Research, Fisheries NSW, Department of Primary Industries, Coffs Harbour, NSW 2450, Australia
| | - Mathew Skye
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Marina Garcia-Pizá
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ezequiel M Marzinelli
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technical University, Singapore 637551, Singapore
| | - Alexandra H Campbell
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Evolution and Ecology Research Centre, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
| | - Enric Ballesteros
- Centre d'Estudis Avançats de Blanes (Consejo Superior de Investigaciones Científicas), 17300 Blanes, Girona, Spain
| | - Andrew S Hoey
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Ana Vila-Concejo
- Geocoastal Research Group, School of Geosciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Yves-Marie Bozec
- Marine Spatial Ecology Lab, Australian Research Council Centre of Excellence for Coral Reef Studies, School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Peter D Steinberg
- Centre for Marine Bio-Innovation, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Sydney Institute of Marine Science, Mosman, NSW 2088, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technical University, Singapore 637551, Singapore
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Bixenmann RJ, Coley PD, Weinhold A, Kursar TA. High herbivore pressure favors constitutive over induced defense. Ecol Evol 2016; 6:6037-49. [PMID: 27648224 PMCID: PMC5016630 DOI: 10.1002/ece3.2208] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 05/05/2016] [Indexed: 11/13/2022] Open
Abstract
UNLABELLED Theoretical and empirical studies show that, when past or current herbivory is a reliable cue of future attack and defenses are costly, defenses can be induced only when needed and thereby permit investment in other functions such as growth or reproduction. Theory also states that, in environments where herbivory is constantly high, constitutive defenses should be favored. Here, we present data to support the second aspect of the induced resistance hypothesis. We examined herbivore-induced responses for four species of Inga (Fabaceae), a common canopy tree in Neotropical forests. We quantified chemical defenses of expanding leaves, including phenolic, saponin and toxic amino acids, in experimental field treatments with and without caterpillars. Because young leaves lack fiber and are higher in protein than mature leaves, they typically lose >25% of their leaf area during the few weeks of expansion. We predicted that the high rates of attack would select for investment in constitutive defenses over induction. Our data show that chemical defenses were quite unresponsive to herbivory. We demonstrated that expanding leaves showed no or only small increases in investment in secondary metabolites, and no qualitative changes in the phenolic compound profile in response to herbivory. The proteinogenic amino acid tyrosine, which can be toxic at high concentrations, showed the greatest levels of induction. SYNTHESIS These results provide some of the first support for theoretical predictions that the evolution of induced vs. constitutive defenses depends on the risk of herbivory. In habitats with constant and high potential losses to herbivores, such as tropical rainforests, high investments in constitutive defenses are favored over induction.
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Affiliation(s)
- Ryan J. Bixenmann
- Department of BiologyUniversity of Utah257S 1400ESalt Lake CityUtah84112
| | - Phyllis D. Coley
- Department of BiologyUniversity of Utah257S 1400ESalt Lake CityUtah84112
- Smithsonian Tropical Research InstituteBox 0843‐03092BalboaRepublic of Panama
| | - Alexander Weinhold
- Department of BiologyUniversity of Utah257S 1400ESalt Lake CityUtah84112
- German Centre for Integrative Biodiversity Research (iDiv), Halle‐Jena‐LeipzigDeutscher Platz 5eLeipzig04103Germany
| | - Thomas A. Kursar
- Department of BiologyUniversity of Utah257S 1400ESalt Lake CityUtah84112
- Smithsonian Tropical Research InstituteBox 0843‐03092BalboaRepublic of Panama
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López-Carretero A, Boege K, Díaz-Castelazo C, Domínguez Z, Rico-Gray V. Influence of plant resistance traits in selectiveness and species strength in a tropical plant-herbivore network. Am J Bot 2016; 103:1436-1448. [PMID: 27539260 DOI: 10.3732/ajb.1600045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 06/20/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Plant-herbivore networks are highly specialized in their interactions, yet they are highly variable with regard to the relative importance of specific host species for herbivores. How host species traits determine specialization and species strength in this antagonistic network is still an unanswered question that we addressed in this study. METHODS We assessed plant cover and antiherbivore resistance traits to assess the extent to which they accounted for the variation in specialization and strength of interactions among species in a plant-herbivore network. We studied a tropical antagonistic network including a diverse herbivore-host plant assemblages in different habitat types and climatic seasons, including host plants with different life histories. KEY RESULTS Particular combinations of leaf toughness, trichome density, and phenolic compounds influenced herbivore specialization and host species strength, but with a significant spatiotemporal variation among plant life histories. Conversely, plant-herbivore network parameters were not influenced by plant cover. CONCLUSIONS Our study highlights the importance of species-specific resistance traits of plants to understand the ecological and evolutionary consequences of plant-herbivore interaction networks. The novelty of our research lies in the use of a trait-based approach to understand the variation observed in diverse plant-herbivore networks.
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Affiliation(s)
| | - Karina Boege
- Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
| | | | - Zaira Domínguez
- Unidad de Servicios de Apoyo en Resolución Analítica, Universidad Veracruzana, Xalapa, Veracruz, México
| | - Víctor Rico-Gray
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz, México
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Holland EP, Gormley AM, Pech RP. Species- and site-specific impacts of an invasive herbivore on tree survival in mixed forests. Ecol Evol 2016; 6:1954-66. [PMID: 27066221 PMCID: PMC4767877 DOI: 10.1002/ece3.2002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 01/15/2016] [Accepted: 01/23/2016] [Indexed: 11/11/2022] Open
Abstract
Invasive herbivores are often managed to limit their negative impact on plant populations, but herbivore density - plant damage relationships are notoriously spatially and temporally variable. Site and species characteristics (both plant and herbivore) must be considered when assessing the potential for herbivore damage, making it difficult to set thresholds for efficient management. Using the invasive brushtail possum Trichosurus vulpecula in New Zealand as a case study, we parameterized a generic model to predict annual probability of browse-induced mortality of five tree species at 12 sites. We compared predicted and observed tree mortality for each species + site combination to establish herbivore abundance - tree mortality thresholds for each site on a single and combined tree species basis. Model results indicated it is likely that possum browse was the primary cause of all tree mortality at nine of the 12 species-site combinations, allowing us to estimate site-specific thresholds below which possum population numbers should be reduced and maintained to keep tree mortality under a predetermined level, for example 0.5% per year. The browse model can be used to set site- and species-specific management action thresholds, and can be adapted easily for other plant or herbivore species. Results for multiple plant or herbivore species at a single site can be combined to create conservative, site-wide management strategies, and used to: determine which sites will be affected most by changes in herbivore abundance; quantify thresholds for herbivore management; and justify expenditure on herbivore control.
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Affiliation(s)
- E Penelope Holland
- Landcare Research PO Box 69040 Lincoln 7640 New Zealand; Department of Biology University of York Heslington York YO10 5DD UK
| | | | - Roger P Pech
- Landcare Research PO Box 69040 Lincoln 7640 New Zealand
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van Dam NM, Bouwmeester HJ. Metabolomics in the Rhizosphere: Tapping into Belowground Chemical Communication. Trends Plant Sci 2016; 21:256-265. [PMID: 26832948 DOI: 10.1016/j.tplants.2016.01.008] [Citation(s) in RCA: 252] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 12/18/2015] [Accepted: 01/06/2016] [Indexed: 05/19/2023]
Abstract
The rhizosphere is densely populated with a variety of organisms. Interactions between roots and rhizosphere community members are mostly achieved via chemical communication. Root exudates contain an array of primary and secondary plant metabolites that can attract, deter, or kill belowground insect herbivores, nematodes, and microbes, and inhibit competing plants. Metabolomics of root exudates can potentially help us to better understand this chemical dialogue. The main limitations are the proper sampling of the exudate, the sensitivity of the metabolomics platforms, and the multivariate data analysis to identify causal relations. Novel technologies may help to generate a spatially explicit metabolome of the root and its exudates at a scale that is relevant for the rhizosphere community.
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Affiliation(s)
- Nicole M van Dam
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany; Institute of Ecology, Friedrich Schiller University Jena, Dornburger-Str. 159, 07743 Jena, Germany; Molecular Interaction Ecology, Institute of Water and Wetland Research (IWWR), Radboud University, PO Box 9010, Nijmegen, GL 6500, The Netherlands.
| | - Harro J Bouwmeester
- Laboratory of Plant Physiology, Wageningen University, Droevendaalsesteeg 1, Wageningen, PB 6708, The Netherlands.
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Marinosci C, Magalhães S, Macke E, Navajas M, Carbonell D, Devaux C, Olivieri I. Effects of host plant on life-history traits in the polyphagous spider mite Tetranychus urticae. Ecol Evol 2015; 5:3151-8. [PMID: 26356681 PMCID: PMC4559057 DOI: 10.1002/ece3.1554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 05/04/2015] [Indexed: 11/10/2022] Open
Abstract
Studying antagonistic coevolution between host plants and herbivores is particularly relevant for polyphagous species that can experience a great diversity of host plants with a large range of defenses. Here, we performed experimental evolution with the polyphagous spider mite Tetranychus urticae to detect how mites can exploit host plants. We thus compared on a same host the performance of replicated populations from an ancestral one reared for hundreds of generations on cucumber plants that were shifted to either tomato or cucumber plants. We controlled for maternal effects by rearing females from all replicated populations on either tomato or cucumber leaves, crossing this factor with the host plant in a factorial design. About 24 generations after the host shift and for all individual mites, we measured the following fitness components on tomato leaf fragments: survival at all stages, acceptance of the host plant by juvenile and adult mites, longevity, and female fecundity. The host plant on which mite populations had evolved did not affect the performance of the mites, but only affected their sex ratio. Females that lived on tomato plants for circa 24 generations produced a higher proportion of daughters than did females that lived on cucumber plants. In contrast, maternal effects influenced juvenile survival, acceptance of the host plant by adult mites and female fecundity. Independently of the host plant species on which their population had evolved, females reared on the tomato maternal environment produced offspring that survived better on tomato as juveniles, but accepted less this host plant as adults and had a lower fecundity than did females reared on the cucumber maternal environment. We also found that temporal blocks affected mite dispersal and both female longevity and fecundity. Taken together, our results show that the host plant species can affect critical parameters of population dynamics, and most importantly that maternal and environmental conditions can facilitate colonization and exploitation of a novel host in the polyphagous T. urticae, by affecting dispersal behavior (host acceptance) and female fecundity.
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Affiliation(s)
- Cassandra Marinosci
- ISEM, Institut des Sciences de l'Evolution Montpellier, UMR 5554 (Université de Montpellier/CNRS/IRD) Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
| | - Sara Magalhães
- CE3C, Centre for Ecology, Evolution and Environmental Sciences, Faculdade de Ciências da Universidade de Lisboa Edificio C2, 3° Piso, Campo Grande, P-1749016, Lisbon, Portugal
| | - Emilie Macke
- Laboratory Aquatic Biology, KU Leuven Kulak E. Sabbelaan 53, 8500, Kortrijk, Belgium
| | - Maria Navajas
- INRA UMR CBGP (INRA/IRD/Cirad/Montpellier SupAgro) Campus International de Baillarguet, CS 30016, F-34988, Montferrier-sur-Lez Cedex, France
| | - David Carbonell
- CNRS, Institut des Sciences de l'Evolution Montpellier, UMR 5554 (Université de Montpellier/CNRS/IRD) Bât. 22, Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
| | - Céline Devaux
- ISEM, Institut des Sciences de l'Evolution Montpellier, UMR 5554 (Université de Montpellier/CNRS/IRD) Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
| | - Isabelle Olivieri
- ISEM, Institut des Sciences de l'Evolution Montpellier, UMR 5554 (Université de Montpellier/CNRS/IRD) Place Eugène Bataillon, 34095, Montpellier Cedex 05, France
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Schuldt A, Bruelheide H, Härdtle W, Assmann T, Li Y, Ma K, von Oheimb G, Zhang J. Early positive effects of tree species richness on herbivory in a large-scale forest biodiversity experiment influence tree growth. J Ecol 2015; 103:563-571. [PMID: 26690688 PMCID: PMC4672697 DOI: 10.1111/1365-2745.12396] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/09/2015] [Indexed: 05/31/2023]
Abstract
Despite the importance of herbivory for the structure and functioning of species-rich forests, little is known about how herbivory is affected by tree species richness, and more specifically by random vs. non-random species loss. We assessed herbivore damage and its effects on tree growth in the early stage of a large-scale forest biodiversity experiment in subtropical China that features random and non-random extinction scenarios of tree mixtures numbering between one and 24 species. In contrast to random species loss, the non-random extinction scenarios were based on the tree species' local rarity and specific leaf area - traits that may strongly influence the way herbivory is affected by plant species richness. Herbivory increased with tree species richness across all scenarios and was unaffected by the different species compositions in the random and non-random extinction scenarios. Whereas tree growth rates were positively related to herbivory on plots with smaller trees, growth rates significantly declined with increasing herbivory on plots with larger trees. Our results suggest that the effects of herbivory on growth rates increase from monocultures to the most species-rich plant communities and that negative effects with increasing tree species richness become more pronounced with time as trees grow larger. Synthesis. Our results indicate that key trophic interactions can be quick to become established in forest plantations (i.e. already 2.5 years after tree planting). Stronger herbivory effects on tree growth with increasing tree species richness suggest a potentially important role of herbivory in regulating ecosystem functions and the structural development of species-rich forests from the very start of secondary forest succession. The lack of significant differences between the extinction scenarios, however, contrasts with findings from natural forests of higher successional age, where rarity had negative effects on herbivory. This indicates that the effects of non-random species loss could change with forest succession.
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Affiliation(s)
- Andreas Schuldt
- Institute of Ecology, Leuphana University LüneburgScharnhorststr. 1, D-21335, Lüneburg, Germany
| | - Helge Bruelheide
- Institute of Biology/Geobotany and Botanical Garden, University of HalleAm Kirchtor 1, D-06108, Halle, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-LeipzigDeutscher Platz 5e, D-04103, Leipzig, Germany
| | - Werner Härdtle
- Institute of Ecology, Leuphana University LüneburgScharnhorststr. 1, D-21335, Lüneburg, Germany
| | - Thorsten Assmann
- Institute of Ecology, Leuphana University LüneburgScharnhorststr. 1, D-21335, Lüneburg, Germany
| | - Ying Li
- Institute of Ecology, Leuphana University LüneburgScharnhorststr. 1, D-21335, Lüneburg, Germany
| | - Keping Ma
- Institute of Botany, Chinese Academy of SciencesBeijing, 100093, China
| | - Goddert von Oheimb
- Institute of General Ecology and Environmental Protection, Technische Universität DresdenPienner Str. 7, D-01737, Tharandt, Germany
| | - Jiayong Zhang
- Institute of Ecology, Zhejiang Normal UniversityYinbing Road 688, 321004, Jinhua, China
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Goldman-Huertas B, Mitchell RF, Lapoint RT, Faucher CP, Hildebrand JG, Whiteman NK. Evolution of herbivory in Drosophilidae linked to loss of behaviors, antennal responses, odorant receptors, and ancestral diet. Proc Natl Acad Sci U S A 2015; 112:3026-31. [PMID: 25624509 DOI: 10.1073/pnas.1424656112] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Herbivory is a key innovation in insects, yet has only evolved in one-third of living orders. The evolution of herbivory likely involves major behavioral changes mediated by remodeling of canonical chemosensory modules. Herbivorous flies in the genus Scaptomyza (Drosophilidae) are compelling species in which to study the genomic architecture linked to the transition to herbivory because they recently evolved from microbe-feeding ancestors and are closely related to Drosophila melanogaster. We found that Scaptomyza flava, a leaf-mining specialist on plants in the family (Brassicaceae), was not attracted to yeast volatiles in a four-field olfactometer assay, whereas D. melanogaster was strongly attracted to these volatiles. Yeast-associated volatiles, especially short-chain aliphatic esters, elicited strong antennal responses in D. melanogaster, but weak antennal responses in electroantennographic recordings from S. flava. We sequenced the genome of S. flava and characterized this species' odorant receptor repertoire. Orthologs of odorant receptors, which detect yeast volatiles in D. melanogaster and mediate critical host-choice behavior, were deleted or pseudogenized in the genome of S. flava. These genes were lost step-wise during the evolution of Scaptomyza. Additionally, Scaptomyza has experienced gene duplication and likely positive selection in paralogs of Or67b in D. melanogaster. Olfactory sensory neurons expressing Or67b are sensitive to green-leaf volatiles. Major trophic shifts in insects are associated with chemoreceptor gene loss as recently evolved ecologies shape sensory repertoires.
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