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Martin RA, Tate AT. Pleiotropy alleviates the fitness costs associated with resource allocation trade-offs in immune signalling networks. Proc Biol Sci 2024; 291:20240446. [PMID: 38835275 DOI: 10.1098/rspb.2024.0446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 05/03/2024] [Indexed: 06/06/2024] Open
Abstract
Many genes and signalling pathways within plant and animal taxa drive the expression of multiple organismal traits. This form of genetic pleiotropy instigates trade-offs among life-history traits if a mutation in the pleiotropic gene improves the fitness contribution of one trait at the expense of another. Whether or not pleiotropy gives rise to conflict among traits, however, likely depends on the resource costs and timing of trait deployment during organismal development. To investigate factors that could influence the evolutionary maintenance of pleiotropy in gene networks, we developed an agent-based model of co-evolution between parasites and hosts. Hosts comprise signalling networks that must faithfully complete a developmental programme while also defending against parasites, and trait signalling networks could be independent or share a pleiotropic component as they evolved to improve host fitness. We found that hosts with independent developmental and immune networks were significantly more fit than hosts with pleiotropic networks when traits were deployed asynchronously during development. When host genotypes directly competed against each other, however, pleiotropic hosts were victorious regardless of trait synchrony because the pleiotropic networks were more robust to parasite manipulation, potentially explaining the abundance of pleiotropy in immune systems despite its contribution to life history trade-offs.
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Affiliation(s)
- Reese A Martin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37235, USA
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37235, USA
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Song B, Chen J, Lev-Yadun S, Niu Y, Gao Y, Ma R, Armbruster WS, Sun H. Multifunctionality of angiosperm floral bracts: a review. Biol Rev Camb Philos Soc 2024; 99:1100-1120. [PMID: 38291834 DOI: 10.1111/brv.13060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/02/2024] [Accepted: 01/22/2024] [Indexed: 02/01/2024]
Abstract
Floral bracts (bracteoles, cataphylls) are leaf-like organs that subtend flowers or inflorescences but are of non-floral origin; they occur in a wide diversity of species, representing multiple independent origins, and exhibit great variation in form and function. Although much attention has been paid to bracts over the past 150 years, our understanding of their adaptive significance remains remarkably incomplete. This is because most studies of bract function and evolution focus on only one or a few selective factors. It is widely recognised that bracts experience selection mediated by pollinators, particularly for enhancing pollinator attraction through strong visual, olfactory, or echo-acoustic contrast with the background and through signalling the presence of pollinator rewards, either honestly (providing rewards for pollinators), or deceptively (attraction without reward or even trapping pollinators). However, studies in recent decades have demonstrated that bract evolution is also affected by agents other than pollinators. Bracts can protect flowers, fruits, or seeds from herbivores by displaying warning signals, camouflaging conspicuous reproductive organs, or by providing physical barriers or toxic chemicals. Reviews of published studies show that bracts can also promote seed dispersal and ameliorate the effects of abiotic stressors, such as low temperature, strong ultraviolet radiation, heavy rain, drought, and/or mechanical abrasion, on reproductive organs or for the plants' pollinators. In addition, green bracts and greening of colourful bracts after pollination promote photosynthetic activity, providing substantial carbon (photosynthates) for fruit or seed development, especially late in a plant's life cycle or season, when leaves have started to senesce. A further layer of complexity derives from the fact that the agents of selection driving the evolution of bracts vary between species and even between different developmental stages within a species, and selection by one agent can be reinforced or opposed by other agents. In summary, our survey of the literature reveals that bracts are multifunctional and subject to multiple agents of selection. To understand fully the functional and evolutionary significance of bracts, it is necessary to consider multiple selection agents throughout the life of the plant, using integrative approaches to data collection and analysis.
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Affiliation(s)
- Bo Song
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Jiaqi Chen
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
- School of Life Sciences, Yunnan University, Huannan Road, East of University Town, Chenggong New Area, Kunming, 650500, China
| | - Simcha Lev-Yadun
- Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa at Oranim, Kiryat Tiv'on, 36006, Israel
| | - Yang Niu
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - Yongqian Gao
- Yunnan Forestry Technological College, 1 Jindian, Kunming, 650224, China
| | - Rong Ma
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
| | - W Scott Armbruster
- School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth, PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska, PO Box 757000, Fairbanks, AK, 99775, USA
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China
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Martin R, Tate AT. Pleiotropy alleviates the fitness costs associated with resource allocation trade-offs in immune signaling networks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561276. [PMID: 37873469 PMCID: PMC10592669 DOI: 10.1101/2023.10.06.561276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Many genes and signaling pathways within plant and animal taxa drive the expression of multiple organismal traits. This form of genetic pleiotropy instigates trade-offs among life-history traits if a mutation in the pleiotropic gene improves the fitness contribution of one trait at the expense of another. Whether or not pleiotropy gives rise to conflict among traits, however, likely depends on the resource costs and timing of trait deployment during organismal development. To investigate factors that could influence the evolutionary maintenance of pleiotropy in gene networks, we developed an agent-based model of co-evolution between parasites and hosts. Hosts comprise signaling networks that must faithfully complete a developmental program while also defending against parasites, and trait signaling networks could be independent or share a pleiotropic component as they evolved to improve host fitness. We found that hosts with independent developmental and immune networks were significantly more fit than hosts with pleiotropic networks when traits were deployed asynchronously during development. When host genotypes directly competed against each other, however, pleiotropic hosts were victorious regardless of trait synchrony because the pleiotropic networks were more robust to parasite manipulation, potentially explaining the abundance of pleiotropy in immune systems despite its contribution to life history trade-offs.
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Affiliation(s)
- Reese Martin
- Department of Biological Sciences, Vanderbilt University, Nashville TN, 37235
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, USA
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville TN, 37235
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, USA
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Martin RA, Tate AT. Pleiotropy promotes the evolution of inducible immune responses in a model of host-pathogen coevolution. PLoS Comput Biol 2023; 19:e1010445. [PMID: 37022993 PMCID: PMC10079112 DOI: 10.1371/journal.pcbi.1010445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 02/23/2023] [Indexed: 04/07/2023] Open
Abstract
Components of immune systems face significant selective pressure to efficiently use organismal resources, mitigate infection, and resist parasitic manipulation. A theoretically optimal immune defense balances investment in constitutive and inducible immune components depending on the kinds of parasites encountered, but genetic and dynamic constraints can force deviation away from theoretical optima. One such potential constraint is pleiotropy, the phenomenon where a single gene affects multiple phenotypes. Although pleiotropy can prevent or dramatically slow adaptive evolution, it is prevalent in the signaling networks that compose metazoan immune systems. We hypothesized that pleiotropy is maintained in immune signaling networks despite slowed adaptive evolution because it provides some other advantage, such as forcing network evolution to compensate in ways that increase host fitness during infection. To study the effects of pleiotropy on the evolution of immune signaling networks, we used an agent-based modeling approach to evolve a population of host immune systems infected by simultaneously co-evolving parasites. Four kinds of pleiotropic restrictions on evolvability were incorporated into the networks, and their evolutionary outcomes were compared to, and competed against, non-pleiotropic networks. As the networks evolved, we tracked several metrics of immune network complexity, relative investment in inducible and constitutive defenses, and features associated with the winners and losers of competitive simulations. Our results suggest non-pleiotropic networks evolve to deploy highly constitutive immune responses regardless of parasite prevalence, but some implementations of pleiotropy favor the evolution of highly inducible immunity. These inducible pleiotropic networks are no less fit than non-pleiotropic networks and can out-compete non-pleiotropic networks in competitive simulations. These provide a theoretical explanation for the prevalence of pleiotropic genes in immune systems and highlight a mechanism that could facilitate the evolution of inducible immune responses.
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Affiliation(s)
- Reese A. Martin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Ann T. Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Evolutionary Studies Initiative, Vanderbilt University, Nashville, Tennessee, United States of America
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Wurdack KJ. A new, disjunct species of Bahiana (Euphorbiaceae, Acalyphoideae): Phytogeographic connections between the seasonally dry tropical forests of Peru and Brazil, and a review of spinescence in the family. PHYTOKEYS 2023; 219:121-144. [PMID: 37252447 PMCID: PMC10209711 DOI: 10.3897/phytokeys.219.95872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 01/19/2023] [Indexed: 05/31/2023]
Abstract
Bahiana is expanded from 1 to 2 species with the description of B.occidentalis K. Wurdack, sp. nov. as a new endemic of the seasonally dry tropical forests (SDTFs) of Peru. The disjunct distribution of Bahiana with populations of B.occidentalis on opposite sides of the Andes in northwestern Peru (Tumbes, San Martín) and B.pyriformis in eastern Brazil (Bahia) adds to the phytogeographic links among the widely scattered New World SDTFs. Although B.occidentalis remains imperfectly known due to the lack of flowering collections, molecular phylogenetic results from four loci (plastid matK, rbcL, and trnL-F; and nuclear ITS) unite the two species as does gross vegetative morphology, notably their spinose stipules, and androecial structure. Spinescence in Euphorbiaceae was surveyed and found on vegetative organs in 25 genera, which mostly have modified sharp branch tips. Among New World taxa, spines that originate from stipule modifications only occur in Bahiana and Acidocroton, while the intrastipular spines of Philyra are of uncertain homologies.
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Affiliation(s)
- Kenneth J. Wurdack
- Department of Botany, MRC-166, National Museum of Natural History, Smithsonian Institution, P.O. Box 37012, Washington DC 20013-7012, USANational Museum of Natural HistoryWashington DCUnited States of America
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Edaphic specialization onto bare, rocky outcrops as a factor in the evolution of desert angiosperms. Proc Natl Acad Sci U S A 2023; 120:e2214729120. [PMID: 36716359 PMCID: PMC9963280 DOI: 10.1073/pnas.2214729120] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Understanding the processes that enable organisms to shift into more arid environments as they emerge is critical for gauging resilience to climate change, yet these forces remain poorly known. In a comprehensive clade-based study, we investigate recent shifts into North American deserts in the rock daisies (tribe Perityleae), a diverse tribe of desert sunflowers (Compositae). We sample rock daisies across two separate contact zones between tropical deciduous forest and desert biomes in western North America and infer a time-calibrated phylogeny based on target capture sequence data. We infer biome shifts using Bayesian inference with paleobiome-informed models and find evidence for seven independent shifts into desert habitats since the onset of aridification in the late Miocene. The earliest shift occurred out of tropical deciduous forests and led to an extensive radiation throughout North American deserts that accounts for the majority of extant desert rock daisies. Estimates of life history and micro-habitat in the rock daisies reveal a correlation between a suffrutescent perennial life history and edaphic endemism onto rocky outcrops, an ecological specialization that evolved prior to establishment and diversification in deserts. That the insular radiation of desert rock daisies stemmed from ancestors preadapted for dry conditions as edaphic endemics in otherwise densely vegetated tropical deciduous forests in northwest Mexico underscores the crucial role of exaptation and dispersal for shifts into arid environments.
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Rushworth CA, Wagner MR, Mitchell-Olds T, Anderson JT. The Boechera model system for evolutionary ecology. AMERICAN JOURNAL OF BOTANY 2022; 109:1939-1961. [PMID: 36371714 DOI: 10.1002/ajb2.16090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 08/27/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Model systems in biology expand the research capacity of individuals and the community. Closely related to Arabidopsis, the genus Boechera has emerged as an important ecological model owing to the ability to integrate across molecular, functional, and eco-evolutionary approaches. Boechera species are broadly distributed in relatively undisturbed habitats predominantly in western North America and provide one of the few experimental systems for identification of ecologically important genes through genome-wide association studies and investigations of selection with plants in their native habitats. The ecologically, evolutionarily, and agriculturally important trait of apomixis (asexual reproduction via seeds) is common in the genus, and field experiments suggest that abiotic and biotic environments shape the evolution of sex. To date, population genetic studies have focused on the widespread species B. stricta, detailing population divergence and demographic history. Molecular and ecological studies show that balancing selection maintains genetic variation in ~10% of the genome, and ecological trade-offs contribute to complex trait variation for herbivore resistance, flowering phenology, and drought tolerance. Microbiome analyses have shown that host genotypes influence leaf and root microbiome composition, and the soil microbiome influences flowering phenology and natural selection. Furthermore, Boechera offers numerous opportunities for investigating biological responses to global change. In B. stricta, climate change has induced a shift of >2 weeks in the timing of first flowering since the 1970s, altered patterns of natural selection, generated maladaptation in previously locally-adapted populations, and disrupted life history trade-offs. Here we review resources and results for this eco-evolutionary model system and discuss future research directions.
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Affiliation(s)
| | - Maggie R Wagner
- Department of Ecology and Evolutionary Biology, Kansas Biological Survey and Center for Ecological Research, University of Kansas, Lawrence, KS, 66045, USA
| | | | - Jill T Anderson
- Department of Genetics and Odum School of Ecology, University of Georgia, Athens, GA, 30602, USA
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McPeek SJ, Bronstein JL, McPeek MA. Eco-evolutionary feedbacks among pollinators, herbivores, and their plant resources. Evolution 2022; 76:1287-1300. [PMID: 35420697 PMCID: PMC9321553 DOI: 10.1111/evo.14492] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 03/19/2022] [Accepted: 03/23/2022] [Indexed: 01/21/2023]
Abstract
Eco-evolutionary feedbacks among multiple species occur when one species affects another species' evolution via its effects on the abundance and traits of a shared partner species. What happens if those two species enact opposing effects on their shared partner's population growth? Furthermore, what if those two kinds of interactions involve separate traits? For example, many plants produce distinct suites of traits that attract pollinators (mutualists) and deter herbivores (antagonists). Here, we develop a model to explore how pollinators and herbivores may influence each other's interactions with a shared plant species via evolutionary effects on the plant's nectar and toxin traits. The model results predict that herbivores indirectly select for the evolution of increased nectar production by suppressing plant population growth. The model also predicts that pollinators indirectly select for the evolution of increased toxin production by plants and increased counterdefenses by herbivores via their positive effects on plant population growth. Unless toxins directly affect pollinator foraging, plants always evolve increases in attraction and defense traits when they interact with both kinds of foragers. This work highlights the value of incorporating ecological dynamics to understand the entangled evolution of mutualisms and antagonisms in natural communities.
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Affiliation(s)
- Sarah J. McPeek
- Department of BiologyUniversity of VirginiaCharlottesvilleVA22904USA
| | - Judith L. Bronstein
- Department of Ecology & Evolutionary BiologyUniversity of ArizonaTucsonAZ85721USA
| | - Mark A. McPeek
- Department of Biological SciencesDartmouth CollegeHanoverNH03755USA
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Carneiro de Melo Moura C, Setyaningsih CA, Li K, Merk MS, Schulze S, Raffiudin R, Grass I, Behling H, Tscharntke T, Westphal C, Gailing O. Biomonitoring via DNA metabarcoding and light microscopy of bee pollen in rainforest transformation landscapes of Sumatra. BMC Ecol Evol 2022; 22:51. [PMID: 35473550 PMCID: PMC9040256 DOI: 10.1186/s12862-022-02004-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 04/07/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Intense conversion of tropical forests into agricultural systems contributes to habitat loss and the decline of ecosystem functions. Plant-pollinator interactions buffer the process of forest fragmentation, ensuring gene flow across isolated patches of forests by pollen transfer. In this study, we identified the composition of pollen grains stored in pot-pollen of stingless bees, Tetragonula laeviceps, via dual-locus DNA metabarcoding (ITS2 and rbcL) and light microscopy, and compared the taxonomic coverage of pollen sampled in distinct land-use systems categorized in four levels of management intensity (forest, shrub, rubber, and oil palm) for landscape characterization. RESULTS Plant composition differed significantly between DNA metabarcoding and light microscopy. The overlap in the plant families identified via light microscopy and DNA metabarcoding techniques was low and ranged from 22.6 to 27.8%. Taxonomic assignments showed a dominance of pollen from bee-pollinated plants, including oil-bearing crops such as the introduced species Elaeis guineensis (Arecaceae) as one of the predominant taxa in the pollen samples across all four land-use types. Native plant families Moraceae, Euphorbiaceae, and Cannabaceae appeared in high proportion in the analyzed pollen material. One-way ANOVA (p > 0.05), PERMANOVA (R² values range from 0.14003 to 0.17684, for all tests p-value > 0.5), and NMDS (stress values ranging from 0.1515 to 0.1859) indicated a lack of differentiation between the species composition and diversity of pollen type in the four distinct land-use types, supporting the influx of pollen from adjacent areas. CONCLUSIONS Stingless bees collected pollen from a variety of agricultural crops, weeds, and wild plants. Plant composition detected at the family level from the pollen samples likely reflects the plant composition at the landscape level rather than the plot level. In our study, the plant diversity in pollen from colonies installed in land-use systems with distinct levels of forest transformation was highly homogeneous, reflecting a large influx of pollen transported by stingless bees through distinct land-use types. Dual-locus approach applied in metabarcoding studies and visual pollen identification showed great differences in the detection of the plant community, therefore a combination of both methods is recommended for performing biodiversity assessments via pollen identification.
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Affiliation(s)
| | - Christina A Setyaningsih
- Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, 37073, Göttingen, Germany
| | - Kevin Li
- Agroecology, Department of Crop Sciences, University of Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Miryam Sarah Merk
- Statistics and Econometrics, University of Göttingen, Göttingen, Germany
| | - Sonja Schulze
- Agroecology, Department of Crop Sciences, University of Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Rika Raffiudin
- Department of Biology, IPB University ID, Bogor, West Java, 16880, Indonesia
| | - Ingo Grass
- Department of Ecology of Tropical Agricultural Systems, University of Hohenheim, 70599, Stuttgart, Germany
| | - Hermann Behling
- Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, 37073, Göttingen, Germany
| | - Teja Tscharntke
- Agroecology, Department of Crop Sciences, University of Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Catrin Westphal
- Functional Agrobiodiversity, Department of Crop Sciences, University of Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Oliver Gailing
- Department of Forest Genetics and Forest Tree Breeding, University of Göttingen, 37077, Göttingen, Germany. .,Centre of Biodiversity and Sustainable Land Use, University of Göttingen, 37077, Göttingen, Germany.
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Gearty W, Carrillo E, Payne JL. Ecological Filtering and Exaptation in the Evolution of Marine Snakes. Am Nat 2021; 198:506-521. [PMID: 34559607 DOI: 10.1086/716015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractConvergent evolution is often attributed to adaptation of form to function, but it can also result from ecological filtering, exaptation, or nonaptation. Testing among these possibilities is critical to understanding how and why morphological similarities emerge independently in multiple lineages. To address this challenge, we combined multiple preexisting phylogenetic methods to jointly estimate the habitats and morphologies of lineages within a phylogeny. We applied this approach to the invasions of snakes into the marine realm. We utilized a data set for 1,243 extant snake species consisting of newly compiled biome occupancy information and preexisting data on reproductive strategy, body mass, and environmental temperature and elevation. We find evidence for marine clades arising from a variety of aquatic and terrestrial habitats. Furthermore, there is strong evidence of ecological filtering for nonmarine ancestors that were already viviparous, had slightly larger-than-average body sizes, and lived in environments with higher-than-average temperatures and lower-than-average elevations. In aggregate, similarities among independent lineages of marine snakes result from a combination of exaptation and strong ecological filtering. Strong barriers to entry of new habitats appear to be more important than common adaptations following invasions for producing similarities among independent lineages invading a shared, novel habitat.
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Milet-Pinheiro P, Domingos-Melo A, Olivera JB, Albuquerque NSL, Costa ACG, Albuquerque-Lima S, Silva MFR, Navarro DMAF, Maia ACD, Gundersen LL, Schubert M, Dötterl S, Machado IC. A Semivolatile Floral Scent Marks the Shift to a Novel Pollination System in Bromeliads. Curr Biol 2021; 31:860-868.e4. [PMID: 33338429 DOI: 10.1016/j.cub.2020.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 10/29/2020] [Accepted: 11/04/2020] [Indexed: 11/26/2022]
Abstract
Perfume flowers (sensu Vogel1) produce intense scents that function both as attractants and as the sole rewards for pollinators. The scent is collected exclusively by male euglossine bees and used during pre-mating behavior.2-5 Perfume flowers have evolved independently in 15 angiosperm families, with over 1,000 reported species across the Neotropical region.6 Members of Cryptanthus (Bromeliaceae) represent a puzzling exception among perfume flowers, as flowers produce nectar and do not emit a noticeable scent yet still attract euglossine males.7 Here, we studied the pollination ecology of Cryptanthus burle-marxii and decode the chemical communication between its flowers and euglossine males. Field observations revealed euglossine males and hummingbirds as potential pollinators. The bees always contacted anthers/stigma of C. burle-marxii while scraping the petals to obtain chemicals, whereas nectar-seeking hummingbirds normally only contacted the anthers. Based on gas chromatography-mass spectrometry/nuclear magnetic resonance analyses of flower scent samples and bioassays, we identified the diterpene copalol as the only floral scent compound triggering scent-gathering behavior in euglossine males. Unlike euglossine-bee-mediated pollination, hummingbird pollination is ancestral in the Cryptanthus clade, suggesting a case of an ongoing pollinator shift8-10 mediated by the evolution of perfume as a reward. Copalol was previously unknown as a floral scent constituent and represents the heaviest and least-volatile compound known to attract euglossine males. Our study provides the first experimental evidence that semivolatile floral compounds can mediate euglossine bee interactions. Male euglossine pollination in other plant species lacking noticeable floral scents11-13 suggests that semivolatile-mediated pollinator attraction is more widespread than currently appreciated.
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Affiliation(s)
- Paulo Milet-Pinheiro
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil.
| | - Arthur Domingos-Melo
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - João B Olivera
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Nayara S L Albuquerque
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Ana Carolina G Costa
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Sinzinando Albuquerque-Lima
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Marcelo F R Silva
- Department of Fundamental Chemistry, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Daniela M A F Navarro
- Department of Fundamental Chemistry, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
| | - Artur C D Maia
- Departament of Systematics and Ecology, Universidade Federal da Paraíba, 58051-900 João Pessoa, Brazil
| | | | - Mario Schubert
- Department of Biosciences, Paris-Lodron-University of Salzburg, 5020 Salzburg, Austria
| | - Stefan Dötterl
- Department of Biosciences, Paris-Lodron-University of Salzburg, 5020 Salzburg, Austria
| | - Isabel C Machado
- Departament of Botany, Programa de Pós-Graduação em Biologia Vegetal, Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil
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Rusman Q, Lucas-Barbosa D, Poelman EH, Dicke M. Ecology of Plastic Flowers. TRENDS IN PLANT SCIENCE 2019; 24:725-740. [PMID: 31204246 DOI: 10.1016/j.tplants.2019.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Revised: 04/16/2019] [Accepted: 04/25/2019] [Indexed: 05/20/2023]
Abstract
Plant phenotypic plasticity in response to herbivore attack includes changes in flower traits. Such herbivore-induced changes in flower traits have consequences for interactions with flower visitors. We synthesize here current knowledge on the specificity of herbivore-induced changes in flower traits, the underlying molecular mechanisms, and the ecological consequences for flower-associated communities. Herbivore-induced changes in flower traits seem to be largely herbivore species-specific. The extensive plasticity observed in flowers influences a highly connected web of interactions within the flower-associated community. We argue that the adaptive value of herbivore-induced plant responses and flower plasticity can be fully understood only from a community perspective rather than from pairwise interactions.
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Affiliation(s)
- Quint Rusman
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands.
| | - Dani Lucas-Barbosa
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands
| | - Erik H Poelman
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands
| | - Marcel Dicke
- Laboratory of Entomology, Wageningen University, PO Box 16, 6700 AA Wageningen, The Netherlands
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Cardinal-McTeague WM, Wurdack KJ, Sigel EM, Gillespie LJ. Seed size evolution and biogeography of Plukenetia (Euphorbiaceae), a pantropical genus with traditionally cultivated oilseed species. BMC Evol Biol 2019; 19:29. [PMID: 30670006 PMCID: PMC6341577 DOI: 10.1186/s12862-018-1308-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 11/23/2018] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Plukenetia is a small pantropical genus of lianas and vines with variably sized edible oil-rich seeds that presents an ideal system to investigate neotropical and pantropical diversification patterns and seed size evolution. We assessed the biogeography and seed evolution of Plukenetia through phylogenetic analyses of a 5069 character molecular dataset comprising five nuclear and two plastid markers for 86 terminals in subtribe Plukenetiinae (representing 20 of ~ 23 Plukenetia species). Two nuclear genes, KEA1 and TEB, were used for phylogenetic reconstruction for the first time. Our goals were: (1) produce a robust, time-dependent evolutionary framework for Plukenetia using BEAST; (2) reconstruct its biogeographical history with ancestral range estimation in BIOGEOBEARS; (3) define seed size categories; (4) identify patterns of seed size evolution using ancestral state estimation; and (5) conduct regression analyses with putative drivers of seed size using the threshold model. RESULTS Plukenetia was resolved into two major groups, which we refer to as the pinnately- and palmately-veined clades. Our analyses suggest Plukenetia originated in the Amazon or Atlantic Forest of Brazil during the Oligocene (28.7 Mya) and migrated/dispersed between those regions and Central America/Mexico throughout the Miocene. Trans-oceanic dispersals explain the pantropical distribution of Plukenetia, including from the Amazon to Africa in the Early Miocene (17.4 Mya), followed by Africa to Madagascar and Africa to Southeast Asia in the Late Miocene (9.4 Mya) and Pliocene (4.5 Mya), respectively. We infer a single origin of large seeds in the ancestor of Plukenetia. Seed size fits a Brownian motion model of trait evolution and is moderately to strongly associated with plant size, fruit type/dispersal syndrome, and seedling ecology. Biome shifts were not drivers of seed size, although there was a weak association with a transition to fire prone semi-arid savannas. CONCLUSIONS The major relationships among the species of Plukenetia are now well-resolved. Our biogeographical analyses support growing evidence that many pantropical distributions developed by periodic trans-oceanic dispersals throughout the Miocene and Pliocene. Selection on a combination of traits contributed to seed size variation, while movement between forest edge/light gap and canopy niches likely contributed to the seed size extremes in Plukenetia.
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Affiliation(s)
- Warren M. Cardinal-McTeague
- Department of Biology, University of Ottawa, Gendron Hall, Room 160, 30 Marie Curie, Ottawa, Ontario K1N 6N5 Canada
- Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario K1P 6P4 Canada
- Department of Botany, MRC-166, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012 USA
| | - Kenneth J. Wurdack
- Department of Botany, MRC-166, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012 USA
| | - Erin M. Sigel
- Department of Biology, University of Louisiana at Lafayette, Billeaud Hall, Room 108, 410 E. St. Mary Blvd, Lafayette, LA 70503 USA
| | - Lynn J. Gillespie
- Department of Biology, University of Ottawa, Gendron Hall, Room 160, 30 Marie Curie, Ottawa, Ontario K1N 6N5 Canada
- Research and Collections, Canadian Museum of Nature, PO Box 3443, Station D, Ottawa, Ontario K1P 6P4 Canada
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Pichersky E, Raguso RA. Why do plants produce so many terpenoid compounds? THE NEW PHYTOLOGIST 2018; 220:692-702. [PMID: 27604856 DOI: 10.1111/nph.14178] [Citation(s) in RCA: 293] [Impact Index Per Article: 48.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/02/2016] [Indexed: 05/19/2023]
Abstract
All plants synthesize a suite of several hundred terpenoid compounds with roles that include phytohormones, protein modification reagents, anti-oxidants, and more. Different plant lineages also synthesize hundreds of distinct terpenoids, with the total number of such specialized plant terpenoids estimated in the scores of thousands. Phylogenetically restricted terpenoids are implicated in defense or in the attraction of beneficial organisms. A popular hypothesis is that the ability of plants to synthesize new compounds arose incrementally by selection when, as a result of gradual changes in their biotic partners and enemies, the 'old' plant compounds were no longer effective, a process dubbed the 'coevolutionary arms race'. Another hypothesis posits that often the sheer diversity of such compounds provides benefits that a single compound cannot. In this article, we review the unique features of the biosynthetic apparatus of terpenes in plants that facilitate the production of large numbers of distinct terpenoids in each species and how facile genetic and biochemical changes can lead to the further diversification of terpenoids. We then discuss evidence relating to the hypotheses that given ecological functions may be enhanced by the presence of mixtures of terpenes and that the acquisition of new functions by terpenoids may favor their retention once the original functions are lost.
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Affiliation(s)
- Eran Pichersky
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Michigan, MI, 48109, USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, 14853, USA
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Moreira X, Abdala-Roberts L, Galmán A, Francisco M, Fuente MDL, Butrón A, Rasmann S. Assessing the influence of biogeographical region and phylogenetic history on chemical defences and herbivory in Quercus species. PHYTOCHEMISTRY 2018; 153:64-73. [PMID: 29886158 DOI: 10.1016/j.phytochem.2018.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 05/25/2018] [Accepted: 06/02/2018] [Indexed: 06/08/2023]
Abstract
Biogeographical factors and phylogenetic history are key determinants of inter-specific variation in plant defences. However, few studies have conducted broad-scale geographical comparisons of plant defences while controlling for phylogenetic relationships, and, in doing so, none have separated constitutive from induced defences. This gap has limited our understanding of how historical or large-scale processes mediate biogeographical patterns in plant defences since these may be contingent upon shared evolutionary history and phylogenetic constraints. We conducted a phylogenetically-controlled experiment testing for differences in constitutive leaf chemical defences and their inducibility between Palearctic and Nearctic oak species (Quercus, total 18 species). We induced defences in one-year old plants by inflicting damage by gypsy moth larvae (Lymantria dispar), estimated the amount of leaf area consumed, and quantified various groups of phenolic compounds. There was no detectable phylogenetic signal for constitutive or induced levels of most defensive traits except for constitutive condensed tannins, as well as no phylogenetic signal in leaf herbivory. We did, however, find marked differences in defence levels between oak species from each region: Palearctic species had higher levels of constitutive condensed tannins, but less constitutive lignins and less constitutive and induced hydrolysable tannins compared with Nearctic species. Additionally, Palearctic species had lower levels of leaf damage compared with Nearctic species. These differences in leaf damage, lignins and hydrolysable (but not condensed) tannins were lost after accounting for phylogeny, suggesting that geographical structuring of phylogenetic relationships mediated biogeographical differences in defences and herbivore resistance. Together, these findings suggest that historical processes and large-scale drivers have shaped differences in allocation to constitutive defences (and in turn resistance) between Palearctic and Nearctic oaks. Moreover, although evidence of phylogenetic conservatism in the studied traits is rather weak, shared evolutionary history appears to mediate some of these biogeographical patterns in allocation to chemical defences.
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Affiliation(s)
- Xoaquín Moreira
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080 Pontevedra, Galicia, Spain.
| | - Luis Abdala-Roberts
- Departamento de Ecología Tropical, Campus de Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Yucatán, Apartado Postal 4-116, Itzimná, 97000 Mérida, Yucatán, Mexico
| | - Andrea Galmán
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080 Pontevedra, Galicia, Spain
| | - Marta Francisco
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080 Pontevedra, Galicia, Spain
| | - María de la Fuente
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080 Pontevedra, Galicia, Spain
| | - Ana Butrón
- Misión Biológica de Galicia (MBG-CSIC), Apartado de correos 28, 36080 Pontevedra, Galicia, Spain
| | - Sergio Rasmann
- Institute of Biology, Laboratory of Functional Ecology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
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Wininger K, Rank N. Evolutionary dynamics of interactions between plants and their enemies: comparison of herbivorous insects and pathogens. Ann N Y Acad Sci 2017; 1408:46-60. [PMID: 29125186 DOI: 10.1111/nyas.13541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 09/29/2017] [Accepted: 10/04/2017] [Indexed: 01/21/2023]
Abstract
Plants colonized land over 400 million years ago. Shortly thereafter, organisms began to consume terrestrial plant tissue as a nutritional resource. Most plant enemies are plant pathogens or herbivores, and they impose natural selection for plants to evolve defenses. These traits generate selection pressures on enemies. Coevolution between terrestrial plants and their enemies is an important element of the evolutionary history of both groups. However, coevolutionary studies of plant-pathogen interactions have tended to focus on different research topics than plant-herbivore interactions. Specifically, studies of plant-pathogen interactions often adopt a "gene-for-gene" conceptual framework. In contrast, studies of plants and herbivores often investigate escalation or elaboration of plant defense and herbivore adaptations to overcome it. The main exceptions to the general pattern are studies that focus on small, sessile herbivores that share many features with plant pathogens, studies that incorporate both herbivores and pathogens into a single investigation, and studies that test aspects of Thompson's geographic mosaic theory for coevolution. We discuss the implications of these findings for future research.
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Affiliation(s)
- Kerry Wininger
- Department of Biology, Sonoma State University, Rohnert Park, California
| | - Nathan Rank
- Department of Biology, Sonoma State University, Rohnert Park, California
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17
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Hartmann M, Štefánek M, Zdvořák P, Heřman P, Chrtek J, Mráz P. The Red Queen hypothesis and geographical parthenogenesis in the alpine hawkweed Hieracium alpinum (Asteraceae). Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx105] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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18
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Marquis RJ, Salazar D, Baer C, Reinhardt J, Priest G, Barnett K. Ode to Ehrlich and Raven or how herbivorous insects might drive plant speciation. Ecology 2017; 97:2939-2951. [PMID: 27870033 DOI: 10.1002/ecy.1534] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Revised: 06/27/2016] [Accepted: 07/07/2016] [Indexed: 11/06/2022]
Abstract
Fifty years ago, Ehrlich and Raven proposed that insect herbivores have driven much of plant speciation, particularly at tropical latitudes. There have been no explicit tests of their hypotheses. Indeed there were no proposed mechanisms either at the time or since by which herbivores might generate new plant species. Here we outline two main classes of mechanisms, prezygotic and postzygotic, with a number of scenarios in each by which herbivore-driven changes in host plant secondary chemistry might lead to new plant lineage production. The former apply mainly to a sympatric model of speciation while the latter apply to a parapatric or allopatric model. Our review suggests that the steps of each mechanism are known to occur individually in many different systems, but no scenario has been thoroughly investigated in any one system. Nevertheless, studies of Dalechampia and its herbivores and pollinators, and patterns of defense tradeoffs in trees on different soil types in the Peruvian Amazon provide evidence consistent with the original hypotheses of Ehrlich and Raven. For herbivores to drive sympatric speciation, our findings suggest that interactions with both their herbivores and their pollinators should be considered. In contrast, herbivores may drive speciation allopatrically without any influence by pollinators. Finally, there is evidence that these mechanisms are more likely to occur at low latitudes and thus more likely to produce new species in the tropics. The mechanisms we outline provide a predictive framework for further study of the general role that herbivores play in diversification of their host plants.
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Affiliation(s)
- Robert J Marquis
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
| | - Diego Salazar
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA.,Department of Integrative Biology, University of California-Berkeley, 3040 Valley Life Sciences Bldg #3140, Berkeley, California, 94720, USA
| | - Christina Baer
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
| | - Jason Reinhardt
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA.,Department of Forest Resources, University of Minnesota, 1530 Cleveland Ave. N., St. Paul, Minnesota, 55108, USA
| | - Galen Priest
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA
| | - Kirk Barnett
- Department of Biology and Whitney R. Harris World Ecology Center, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri, 63121, USA.,Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, Penrith, New South Wales, 2751, Australia
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19
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Tripp EA, Tsai YHE. Disentangling geographical, biotic, and abiotic drivers of plant diversity in neotropical Ruellia (Acanthaceae). PLoS One 2017; 12:e0176021. [PMID: 28472046 PMCID: PMC5417425 DOI: 10.1371/journal.pone.0176021] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/04/2017] [Indexed: 11/19/2022] Open
Abstract
It has long been hypothesized that biotic interactions are important drivers of biodiversity evolution, yet such interactions have been relatively less studied than abiotic factors owing to the inherent complexity in and the number of types of such interactions. Amongst the most prominent of biotic interactions worldwide are those between plants and pollinators. In the Neotropics, the most biodiverse region on Earth, hummingbird and bee pollination have contributed substantially to plant fitness. Using comparative methods, we test the macroevolutionary consequences of bird and bee pollination within a species rich lineage of flowering plants: Ruellia. We additionally explore impacts of species occupancy of ever-wet rainforests vs. dry ecosystems including cerrado and seasonally dry tropical forests. We compared outcomes based on two different methods of model selection: a traditional approach that utilizes a series of transitive likelihood ratio tests as well as a weighted model averaging approach. Analyses yield evidence for increased net diversification rates among Neotropical Ruellia (compared to Paleotropical lineages) as well as among hummingbird-adapted species. In contrast, we recovered no evidence of higher diversification rates among either bee- or non-bee-adapted lineages and no evidence for higher rates among wet or dry habitat lineages. Understanding fully the factors that have contributed to biases in biodiversity across the planet will ultimately depend upon incorporating knowledge of biotic interactions as well as connecting microevolutionary processes to macroevolutionary patterns.
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Affiliation(s)
- Erin A. Tripp
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, United States of America
- Museum of Natural History, University of Colorado, Boulder, Colorado, United States of America
| | - Yi-Hsin Erica Tsai
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, United States of America
- Museum of Natural History, University of Colorado, Boulder, Colorado, United States of America
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20
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Thompson KA, Cory KA, Johnson MTJ. Induced defences alter the strength and direction of natural selection on reproductive traits in common milkweed. J Evol Biol 2017; 30:1219-1228. [DOI: 10.1111/jeb.13045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 01/22/2017] [Accepted: 01/23/2017] [Indexed: 11/29/2022]
Affiliation(s)
- K. A. Thompson
- Department of Biology; University of Toronto Mississauga; Mississauga ON Canada
- Department of Zoology and Biodiversity Research Centre; University of British Columbia; Vancouver BC Canada
| | - K. A. Cory
- Department of Biology; University of Toronto Mississauga; Mississauga ON Canada
| | - M. T. J. Johnson
- Department of Biology; University of Toronto Mississauga; Mississauga ON Canada
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21
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Jogesh T, Overson RP, Raguso RA, Skogen KA. Herbivory as an important selective force in the evolution of floral traits and pollinator shifts. AOB PLANTS 2016; 9:plw088. [PMID: 28011456 PMCID: PMC5499749 DOI: 10.1093/aobpla/plw088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 11/16/2016] [Accepted: 11/29/2016] [Indexed: 05/09/2023]
Abstract
Floral trait evolution is frequently attributed to pollinator-mediated selection but herbivores can play a key role in shaping plant reproductive biology. Here we examine the role of florivores in driving floral trait evolution and pollinator shifts in a recently radiated clade of flowering plants, Oenothera sect. Calylophus We compare florivory by a specialist, internal feeder, Mompha, on closely related hawkmoth- and bee-pollinated species and document variation in damage based on floral traits within sites, species and among species. Our results show that flowers with longer floral tubes and decreased floral flare have increased Mompha damage. Bee-pollinated flowers, which have substantially smaller floral tubes, experience on average 13% less Mompha florivory than do hawkmoth-pollinated flowers. The positive association between tube length and Mompha damage is evident even within sites of some species, suggesting that Mompha can drive trait differentiation at microevolutionary scales. Given that there are at least two independent shifts from hawkmoth to bee pollination in this clade, florivore-mediated selection on floral traits may have played an important role in facilitating morphological changes associated with transitions from hawkmoth to bee pollination.
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Affiliation(s)
- Tania Jogesh
- Chicago Botanic Garden, 1000 Lake Cook Road Glencoe, IL 60022 USA
| | - Rick P Overson
- Chicago Botanic Garden, 1000 Lake Cook Road Glencoe, IL 60022 USA
| | - Robert A Raguso
- Department of Neurobiology and Behavior, Cornell University, 215 Tower Rd., Ithaca, NY 14853, USA
| | - Krissa A Skogen
- Chicago Botanic Garden, 1000 Lake Cook Road Glencoe, IL 60022 USA
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22
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Thompson KA, Johnson MT. Antiherbivore defenses alter natural selection on plant reproductive traits. Evolution 2016; 70:796-810. [DOI: 10.1111/evo.12900] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/07/2016] [Accepted: 02/26/2016] [Indexed: 01/24/2023]
Affiliation(s)
- Ken A. Thompson
- Department of Ecology and Evolutionary Biology; University of Toronto Mississauga; Mississauga Ontario L5L 1C6 Canada
- Department of Biology; University of Toronto Mississauga; Mississauga Ontario L5L 1C6 Canada
| | - Marc T.J. Johnson
- Department of Ecology and Evolutionary Biology; University of Toronto Mississauga; Mississauga Ontario L5L 1C6 Canada
- Department of Biology; University of Toronto Mississauga; Mississauga Ontario L5L 1C6 Canada
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23
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Martins FM, Cunha-Neto IL, Pereira TM. Floral morphology and anatomy of Dalechampia alata Klotzsch ex Baill. (Euphorbiaceae), with emphasis on secretory structures. BRAZ J BIOL 2016; 76:233-44. [DOI: 10.1590/1519-6984.19514] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 11/26/2014] [Indexed: 11/22/2022] Open
Abstract
Abstract The morphology and anatomy of the flower of Dalechampia alata, as well as the chemical nature of the exudates secreted in the inflorescence were studied using light microscope. This is the first report showing the presence of colleters in the genus Dalechampia. In the staminate flower occur a group of small secretory glands. The histochemical results indicate that the substance secreted from the glands is lipidic and resinuous in nature, while in the colleters it consists of polysaccharides and lipid-rich substances. The ovule of D. alata are anatropous, subglobose and bitegmic. It presents obturator, micropyle occluded by nucellar beak and meristematic activity in the ovary wall. The secretion produced in the stigmatic and transmitting tissue consists of polysaccharides.
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Johnson MT, Campbell SA, Barrett SC. Evolutionary Interactions Between Plant Reproduction and Defense Against Herbivores. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2015. [DOI: 10.1146/annurev-ecolsys-112414-054215] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marc T.J. Johnson
- Department of Biology, University of Toronto at Mississauga, Mississauga, Ontario, L5L 1C6 Canada;
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2 Canada; ,
| | - Stuart A. Campbell
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2 Canada; ,
| | - Spencer C.H. Barrett
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2 Canada; ,
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Cacho NI, Kliebenstein DJ, Strauss SY. Macroevolutionary patterns of glucosinolate defense and tests of defense-escalation and resource availability hypotheses. THE NEW PHYTOLOGIST 2015; 208:915-27. [PMID: 26192213 DOI: 10.1111/nph.13561] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/08/2015] [Indexed: 05/12/2023]
Abstract
We explored macroevolutionary patterns of plant chemical defense in Streptanthus (Brassicaceae), tested for evolutionary escalation of defense, as predicted by Ehrlich and Raven's plant-herbivore coevolutionary arms-race hypothesis, and tested whether species inhabiting low-resource or harsh environments invest more in defense, as predicted by the resource availability hypothesis (RAH). We conducted phylogenetically explicit analyses using glucosinolate profiles, soil nutrient analyses, and microhabitat bareness estimates across 30 species of Streptanthus inhabiting varied environments and soils. We found weak to moderate phylogenetic signal in glucosinolate classes and no signal in total glucosinolate production; a trend toward evolutionary de-escalation in the numbers and diversity of glucosinolates, accompanied by an evolutionary increase in the proportion of aliphatic glucosinolates; some support for the RAH relative to soil macronutrients, but not relative to serpentine soil use; and that the number of glucosinolates increases with microhabitat bareness, which is associated with increased herbivory and drought. Weak phylogenetic signal in chemical defense has been observed in other plant systems. A more holistic approach incorporating other forms of defense might be necessary to confidently reject escalation of defense. That defense increases with microhabitat bareness supports the hypothesis that habitat bareness is an underappreciated selective force on plants in harsh environments.
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Affiliation(s)
- N Ivalú Cacho
- Center for Population Biology, and Department of Evolution of Ecology, University of California, One Shields Avenue, Davis, CA, 95616, USA
- Instituto de Biología, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, 04510, Mexico City, Mexico
| | - Daniel J Kliebenstein
- Department of Plant Sciences, University of California. One Shields Avenue, Davis, CA, 95616, USA
- DynaMo Center of Excellence, University of Copenhagen, Thorvaldsensvej 40, DK-1871, Frederiksberg C, Denmark
| | - Sharon Y Strauss
- Center for Population Biology, and Department of Evolution of Ecology, University of California, One Shields Avenue, Davis, CA, 95616, USA
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Couvillon MJ, Al Toufailia H, Butterfield TM, Schrell F, Ratnieks FLW, Schürch R. Caffeinated forage tricks honeybees into increasing foraging and recruitment behaviors. Curr Biol 2015; 25:2815-2818. [PMID: 26480843 DOI: 10.1016/j.cub.2015.08.052] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 08/19/2015] [Accepted: 08/24/2015] [Indexed: 12/01/2022]
Abstract
In pollination, plants provide food reward to pollinators who in turn enhance plant reproduction by transferring pollen, making the relationship largely cooperative; however, because the interests of plants and pollinators do not always align, there exists the potential for conflict, where it may benefit both to cheat the other [1, 2]. Plants may even resort to chemistry: caffeine, a naturally occurring, bitter-tasting, pharmacologically active secondary compound whose main purpose is to detract herbivores, is also found in lower concentrations in the nectar of some plants, even though nectar, unlike leaves, is made to be consumed by pollinators. [corrected]. A recent laboratory study showed that caffeine may lead to efficient and effective foraging by aiding honeybee memory of a learned olfactory association [4], suggesting that caffeine may enhance bee reward perception. However, without field data, the wider ecological significance of caffeinated nectar remains difficult to interpret. Here we demonstrate in the field that caffeine generates significant individual- and colony-level effects in free-flying worker honeybees. Compared to a control, a sucrose solution with field-realistic doses of caffeine caused honeybees to significantly increase their foraging frequency, waggle dancing probability and frequency, and persistency and specificity to the forage location, resulting in a quadrupling of colony-level recruitment. An agent-based model also demonstrates how caffeine-enhanced foraging may reduce honey storage. Overall, caffeine causes bees to overestimate forage quality, tempting the colony into sub-optimal foraging strategies, which makes the relationship between pollinator and plant less mutualistic and more exploitative. VIDEO ABSTRACT.
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Affiliation(s)
- Margaret J Couvillon
- Laboratory of Apiculture and Social Insects (LASI), School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
| | - Hasan Al Toufailia
- Laboratory of Apiculture and Social Insects (LASI), School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | | | - Felix Schrell
- Laboratory of Apiculture and Social Insects (LASI), School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Francis L W Ratnieks
- Laboratory of Apiculture and Social Insects (LASI), School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK
| | - Roger Schürch
- Laboratory of Apiculture and Social Insects (LASI), School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK; Clinical Trials Unit (CTU), University of Bern, 3012 Bern, Switzerland
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Pélabon C, Hennet L, Strimbeck R, Johnson H, Armbruster WS. Blossom colour change after pollination provides carbon for developing seeds. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12427] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Lauriane Hennet
- Centre for Biodiversity Dynamics, Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Richard Strimbeck
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - Hansen Johnson
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
| | - W. Scott Armbruster
- Department of Biology Norwegian University of Science and Technology Trondheim 7491 Norway
- School of Biological Sciences University of Portsmouth Portsmouth PO1 2DY UK
- Institute of Arctic Biology University of Alaska Fairbanks AK 99775 USA
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Multiple origins of serpentine-soil endemism explained by preexisting tolerance of open habitats. Proc Natl Acad Sci U S A 2014; 111:14968-9. [PMID: 25313029 DOI: 10.1073/pnas.1417242111] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Occupation of bare habitats, an evolutionary precursor to soil specialization in plants. Proc Natl Acad Sci U S A 2014; 111:15132-7. [PMID: 25267640 DOI: 10.1073/pnas.1409242111] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plant soil specialists contribute greatly to global diversity; however, the ecoevolutionary forces responsible for generating this diversity are poorly understood. We integrate molecular phylogenies with descriptive and experimental ecological data, creating a powerful framework with which to elucidate forces driving soil specialization. Hypotheses explaining edaphic specialization have historically focused on costs of adaptation to elements (e.g., nickel, calcium/magnesium) and accompanying tradeoffs in competitive ability in benign soils. We combine in situ microhabitat data for 37 streptanthoid species (Brassicaceae), soil analyses, and competition experiments with their phylogeny to reconstruct selective forces generating serpentine soil endemism, which has four to five independent origins in this group. Coupling ancestral state reconstruction with phylogenetic independent contrasts, we examine the magnitude and timing of changes in soil and habitat attributes relative to inferred shifts to serpentine. We find large changes in soil chemistry at nodes associated with soil shifts, suggesting that elemental changes occurred concomitantly with soil transitions. In contrast, the amount of bare ground surrounding plants in the field ("bareness"), which is greater in serpentine environments, is conserved across soil-type shifts. Thus, occupation of bare environments preceded shifts to serpentine, and may serve as an evolutionary precursor to harsh elemental soils and environments. In greenhouse experiments, taxa from barer environments are poorer competitors, a tradeoff that may contribute to soil endemism. The hypothesis of occupation of bare habitats as a precursor of soil specialization can be tested in other systems with a similar integrative ecophylogenetic approach, thereby providing deeper insights into this rich source of biodiversity.
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Bohman B, Phillips RD, Menz MHM, Berntsson BW, Flematti GR, Barrow RA, Dixon KW, Peakall R. Discovery of pyrazines as pollinator sex pheromones and orchid semiochemicals: implications for the evolution of sexual deception. THE NEW PHYTOLOGIST 2014; 203:939-952. [PMID: 24697806 DOI: 10.1111/nph.12800] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 03/05/2014] [Indexed: 06/03/2023]
Abstract
Sexually deceptive orchids employ floral volatiles to sexually lure their specific pollinators. How and why this pollination system has evolved independently on multiple continents remains unknown, although preadaptation is considered to have been important. Understanding the chemistry of sexual deception is a crucial first step towards solving this mystery. The combination of gas chromatography-electroantennographic detection (GC-EAD), GC-MS, synthesis and field bioassays allowed us to identify the volatiles involved in the interaction between the orchid Drakaea glyptodon and its sexually attracted male thynnine wasp pollinator, Zaspilothynnus trilobatus. Three alkylpyrazines and one novel hydroxymethyl pyrazine were identified as the sex pheromone of Z. trilobatus and are also used by D. glyptodon for pollinator attraction. Given that our findings revealed a new chemical system for plants, we surveyed widely across representative orchid taxa for the presence of these compounds. With one exception, our chemical survey failed to detect pyrazines in related genera. Collectively, no evidence for preadaptation was found. The chemistry of sexual deception is more diverse than previously known. Our results suggest that evolutionary novelty may have played a key role in the evolution of sexual deception and highlight the value of investigating unusual pollination systems for advancing our understanding of the role of chemistry in evolution.
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Affiliation(s)
- Björn Bohman
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia; Research School of Chemistry, The Australian National University, Canberra, ACT, 0200, Australia; School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, 6009, Australia
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Affiliation(s)
- Anurag A Agrawal
- Department of Ecology and Evolutionary Biology, Cornell University, 425 Corson Hall, 215 Tower Road, Ithaca, NY, 14853, USA
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Von Euler T, Agren J, Ehrlén J. Environmental context influences both the intensity of seed predation and plant demographic sensitivity to attack. Ecology 2014; 95:495-504. [PMID: 24669742 DOI: 10.1890/13-0528.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Variation in mutualistic and antagonistic interactions are important sources of variation in population dynamics and natural selection. Environmental heterogeneity can influence the outcome of interactions by affecting the intensity of interactions, but also by affecting the demography of the populations involved. However, little is known about the relative importance of environmental effects on interaction intensities and demographic sensitivity for variation in population growth rates. We investigated how soil depth, soil moisture, soil nutrient composition, and vegetation height influenced the intensity of seed predation as well as host plant demography and sensitivity to seed predation in the perennial herb Primula farinosa. Intensity of seed predation ranged from 0% to 80% of seeds damaged among the 24 study populations and was related to soil moisture in two of four years. The effect of seed predation on plant population growth rate (lambda) ranged from negligible to a reduction in lambda by 0.70. Sensitivity of population growth rate to predation explained as much of the variation in the reductions in population growth rate due to seed predation as did predation intensity. Plant population growth rate in the absence of seed predation and sensitivity to predation were negatively related to soil depth and soil moisture. Both intensity of predation and sensitivity to predation were positively correlated with potential population growth rate and, as a result, there was no significant relationship between predation intensity and realized population growth rate. We conclude that in our study system environmental context influences the effects of seed predation on plant fitness and population dynamics in two important ways: through variation in interaction intensity and through sensitivity to the effects of this interaction. Moreover, our results show that a given abiotic factor can influence population growth rate in different directions through effects on potential growth rate, intensity of biotic interactions, and the sensitivity of population growth rate to interactions.
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Armbruster WS. Floral specialization and angiosperm diversity: phenotypic divergence, fitness trade-offs and realized pollination accuracy. AOB PLANTS 2014; 6:plu003. [PMID: 24790124 PMCID: PMC4038416 DOI: 10.1093/aobpla/plu003] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/05/2014] [Indexed: 05/08/2023]
Abstract
Plant reproduction by means of flowers has long been thought to promote the success and diversification of angiosperms. It remains unclear, however, how this success has come about. Do flowers, and their capacity to have specialized functions, increase speciation rates or decrease extinction rates? Is floral specialization fundamental or incidental to the diversification? Some studies suggest that the conclusions we draw about the role of flowers in the diversification and increased phenotypic disparity (phenotypic diversity) of angiosperms depends on the system. For orchids, for example, specialized pollination may have increased speciation rates, in part because in most orchids pollen is packed in discrete units so that pollination is precise enough to contribute to reproductive isolation. In most plants, however, granular pollen results in low realized pollination precision, and thus key innovations involving flowers more likely reflect reduced extinction rates combined with opportunities for evolution of greater phenotypic disparity (phenotypic diversity) and occupation of new niches. Understanding the causes and consequences of the evolution of specialized flowers requires knowledge of both the selective regimes and the potential fitness trade-offs in using more than one pollinator functional group. The study of floral function and flowering-plant diversification remains a vibrant evolutionary field. Application of new methods, from measuring natural selection to estimating speciation rates, holds much promise for improving our understanding of the relationship between floral specialization and evolutionary success.
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Affiliation(s)
- W. Scott Armbruster
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, UK
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775-7000, USA
- Department of Biology, Norwegian University of Science & Technology, Trondheim N-7491, Norway
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Boberg E, Alexandersson R, Jonsson M, Maad J, Ågren J, Nilsson LA. Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia. ANNALS OF BOTANY 2014; 113:267-75. [PMID: 24169591 PMCID: PMC3890388 DOI: 10.1093/aob/mct217] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Plant-pollinator interactions are thought to have shaped much of floral evolution. Yet the relative importance of pollinator shifts and coevolutionary interactions for among-population variation in floral traits in animal-pollinated species is poorly known. This study examined the adaptive significance of spur length in the moth-pollinated orchid Platanthera bifolia. METHODS Geographical variation in the length of the floral spur of P. bifolia was documented in relation to variation in the pollinator fauna across Scandinavia, and a reciprocal translocation experiment was conducted in south-east Sweden between a long-spurred woodland population and a short-spurred grassland population. KEY RESULTS Spur length and pollinator fauna varied among regions and habitats, and spur length was positively correlated with the proboscis length of local pollinators. In the reciprocal translocation experiment, long-spurred woodland plants had higher pollination success than short-spurred grassland plants at the woodland site, while no significant difference was observed at the grassland site. CONCLUSIONS The results are consistent with the hypothesis that optimal floral phenotype varies with the morphology of the local pollinators, and that the evolution of spur length in P. bifolia has been largely driven by pollinator shifts.
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Abstract
The major goal of ecological evolutionary developmental biology, also known as "eco-evo-devo," is to uncover the rules that underlie the interactions between an organism's environment, genes, and development and to incorporate these rules into evolutionary theory. In this chapter, we discuss some key and emerging concepts within eco-evo-devo. These concepts show that the environment is a source and inducer of genotypic and phenotypic variation at multiple levels of biological organization, while development acts as a regulator that can mask, release, or create new combinations of variation. Natural selection can subsequently fix this variation, giving rise to novel phenotypes. Combining the approaches of eco-evo-devo and ecological genomics will mutually enrich these fields in a way that will not only enhance our understanding of evolution, but also of the genetic mechanisms underlying the responses of organisms to their natural environments.
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Fernández-Mazuecos M, Blanco-Pastor JL, Gómez JM, Vargas P. Corolla morphology influences diversification rates in bifid toadflaxes (Linaria sect. Versicolores). ANNALS OF BOTANY 2013; 112:1705-22. [PMID: 24142920 PMCID: PMC3838546 DOI: 10.1093/aob/mct214] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
BACKGROUND AND AIMS The role of flower specialization in plant speciation and evolution remains controversial. In this study the evolution of flower traits restricting access to pollinators was analysed in the bifid toadflaxes (Linaria sect. Versicolores), a monophyletic group of ~30 species and subspecies with highly specialized corollas. METHODS A time-calibrated phylogeny based on both nuclear and plastid DNA sequences was obtained using a coalescent-based method, and flower morphology was characterized by means of morphometric analyses. Directional trends in flower shape evolution and trait-dependent diversification rates were jointly analysed using recently developed methods, and morphological shifts were reconstructed along the phylogeny. Pollinator surveys were conducted for a representative sample of species. KEY RESULTS A restrictive character state (narrow corolla tube) was reconstructed in the most recent common ancestor of Linaria sect. Versicolores. After its early loss in the most species-rich clade, this character state has been convergently reacquired in multiple lineages of this clade in recent times, yet it seems to have exerted a negative influence on diversification rates. Comparative analyses and pollinator surveys suggest that the narrow- and broad-tubed flowers are evolutionary optima representing divergent strategies of pollen placement on nectar-feeding insects. CONCLUSIONS The results confirm that different forms of floral specialization can lead to dissimilar evolutionary success in terms of diversification. It is additionally suggested that opposing individual-level and species-level selection pressures may have driven the evolution of pollinator-restrictive traits in bifid toadflaxes.
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Affiliation(s)
- Mario Fernández-Mazuecos
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
- For correspondence. E-mail
| | - José Luis Blanco-Pastor
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
| | - José M. Gómez
- Departamento de Ecología Funcional y Evolutiva, Estación Experimental de Zonas Áridas (EEZA-CSIC), Ctra. Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain
- Departamento de Ecología, Universidad de Granada, Avenida de Fuente Nueva s/n, 18071 Granada, Spain
| | - Pablo Vargas
- Departamento de Biodiversidad y Conservación, Real Jardín Botánico (RJB-CSIC), Plaza de Murillo 2, 28014 Madrid, Spain
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Griffith DM, Anderson TM. Responses of African Grasses in the Genus Sporobolus to Defoliation and Sodium Stress: Tradeoffs, Cross-Tolerance, or Independent Responses? PLANTS 2013; 2:712-25. [PMID: 27137400 PMCID: PMC4844393 DOI: 10.3390/plants2040712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 10/30/2013] [Accepted: 10/31/2013] [Indexed: 12/03/2022]
Abstract
In the Serengeti ecosystem of East Africa, grazing ungulates prefer areas with elevated grass Na, suggesting that some grasses tolerate both high soil Na and defoliation. We performed a factorial Na-by-defoliation greenhouse study with five abundant Sporobolus congeners to explore whether Serengeti grasses possess traits which: (i) confer tolerance to both Na and defoliation (cross-tolerance); (ii) display a tradeoff; or (iii) act independently in their tolerances. Our expectation was that related grasses would exhibit cross-tolerance when simultaneously subjected to Na and defoliation. Instead, we found that physiological tolerances and growth responses to Na and defoliation did not correlate but instead acted independently: species characterized by intense grazing in the field showed no growth or photosynthetic compensation for combined Na and defoliation. Additionally, in all but the highest Na dosage, mortality was higher when species were exposed to both Na and defoliation together. Across species, mortality rates were greater in short-statured species which occur on sodic soils in heavily grazed areas. Mortality among species was positively correlated with specific leaf area, specific root length, and relative growth rate, suggesting that rapidly growing species which invest in low cost tissues have higher rates of mortality when exposed to multiple stressors. We speculate that the prevalence of these species in areas of high Na and disturbance is explained by alternative strategies, such as high fecundity, a wide range of germination conditions, or further dispersal, to compensate for the lack of additional tolerance mechanisms.
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Affiliation(s)
- Daniel M Griffith
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA.
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston-Salem, NC 27109, USA.
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Mutualists and antagonists drive among-population variation in selection and evolution of floral display in a perennial herb. Proc Natl Acad Sci U S A 2013; 110:18202-7. [PMID: 24145439 DOI: 10.1073/pnas.1301421110] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spatial variation in the direction of selection drives the evolution of adaptive differentiation. However, few experimental studies have examined the relative importance of different environmental factors for variation in selection and evolutionary trajectories in natural populations. Here, we combine 8 y of observational data and field experiments to assess the relative importance of mutualistic and antagonistic interactions for spatial variation in selection and short-term evolution of a genetically based floral display dimorphism in the short-lived perennial herb Primula farinosa. Natural populations of this species include two floral morphs: long-scaped plants that present their flowers well above the ground and short-scaped plants with flowers positioned close to the ground. The direction and magnitude of selection on scape morph varied among populations, and so did the frequency of the short morph (median 19%, range 0-100%; n = 69 populations). A field experiment replicated at four sites demonstrated that variation in the strength of interactions with grazers and pollinators were responsible for among-population differences in relative fitness of the two morphs. Selection exerted by grazers favored the short-scaped morph, whereas pollinator-mediated selection favored the long-scaped morph. Moreover, variation in selection among natural populations was associated with differences in morph frequency change, and the experimental removal of grazers at nine sites significantly reduced the frequency of the short-scaped morph over 8 y. The results demonstrate that spatial variation in intensity of grazing and pollination produces a selection mosaic, and that changes in biotic interactions can trigger rapid genetic changes in natural plant populations.
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Difference in defense strategy in flower heads and leaves of Asteraceae: multiple-species approach. Oecologia 2013; 174:227-39. [DOI: 10.1007/s00442-013-2765-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 08/28/2013] [Indexed: 11/26/2022]
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40
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Florivore impacts on plant reproductive success and pollinator mortality in an obligate pollination mutualism. Oecologia 2013; 173:1345-54. [PMID: 23836090 DOI: 10.1007/s00442-013-2694-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 05/23/2013] [Indexed: 10/26/2022]
Abstract
Florivores are present in many pollination systems and can have direct and indirect effects on both plants and pollinators. Although the impact of florivores are commonly examined in facultative pollination mutualisms, their effects on obligate mutualism remain relatively unstudied. Here, we used experimental manipulations and surveys of naturally occurring plants to assess the effect of florivory on the obligate pollination mutualism between yuccas and yucca moths. Yucca filamentosa (Agavaceae) is pollinated by the moth Tegeticula cassandra (Lepidoptera: Prodoxidae), and the mutualism also attracts two florivores: a generalist, the leaf-footed bug Leptoglossus phyllopus (Hemiptera: Coreidae), and a specialist, the beetle Hymenorus densus (Coleoptera: Tenebrionidae). Experimental manipulations of leaf-footed bug densities on side branches of Y. filamentosa inflorescences demonstrated that feeding causes floral abscission but does not reduce pollen or seed production in the remaining flowers. Similar to the leaf-footed bugs, experimental manipulations of beetle densities within individual flowers demonstrated that beetle feeding also causes floral abscission, but, in addition, the beetles also cause a significant reduction in pollen availability. Path analyses of phenotypic selection based on surveys of naturally occurring plants revealed temporal variation in the plant traits important to plant fitness and the effects of the florivores on fitness. Leaf-footed bugs negatively impacted fitness when fewer plants were flowering and leaf-footed bug density was high, whereas beetles had a positive effect on fitness when there were many plants flowering and their densities were low. This positive effect was likely due to adult beetles consuming yucca moth eggs while having a negligible effect on floral abscission. Together, the actions of both florivores either augmented the relationship of plant traits and fitness or slightly weakened the relationship. Overall, the results suggest that, although florivores are always present during flowering, the impact of florivores on phenotypic selection in yuccas is strongly mitigated by changes in their densities on plants from year to year. In contrast, both florivores consistently influenced pollinator larval mortality through floral abscission, and H. densus beetles additionally via the consumption of pollinator eggs.
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Burns MM, Hedin M, Shultz JW. Comparative analyses of reproductive structures in harvestmen (opiliones) reveal multiple transitions from courtship to precopulatory antagonism. PLoS One 2013; 8:e66767. [PMID: 23762497 PMCID: PMC3677920 DOI: 10.1371/journal.pone.0066767] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 05/11/2013] [Indexed: 11/23/2022] Open
Abstract
Explaining the rapid, species-specific diversification of reproductive structures and behaviors is a long-standing goal of evolutionary biology, with recent research tending to attribute reproductive phenotypes to the evolutionary mechanisms of female mate choice or intersexual conflict. Progress in understanding these and other possible mechanisms depends, in part, on reconstructing the direction, frequency and relative timing of phenotypic evolution of male and female structures in species-rich clades. Here we examine evolution of reproductive structures in the leiobunine harvestmen or “daddy long-legs” of eastern North America, a monophyletic group that includes species in which males court females using nuptial gifts and other species that are equipped for apparent precopulatory antagonism (i.e., males with long, hardened penes and females with sclerotized pregenital barriers). We used parsimony- and Bayesian likelihood-based analyses to reconstruct character evolution in categorical reproductive traits and found that losses of ancestral gift-bearing penile sacs are strongly associated with gains of female pregenital barriers. In most cases, both events occur on the same internal branch of the phylogeny. These coevolutionary changes occurred at least four times, resulting in clade-specific designs in the penis and pregenital barrier. The discovery of convergent origins and/or enhancements of apparent precopulatory antagonism among closely related species offers an unusual opportunity to investigate how major changes in reproductive morphology have occurred. We propose new hypotheses that attribute these enhancements to changes in ecology or life history that reduce the duration of breeding seasons, an association that is consistent with female choice, sexual conflict, and/or an alternative evolutionary mechanism.
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Affiliation(s)
- Mercedes M Burns
- Department of Entomology, University of Maryland, College Park, Maryland, United States of America.
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Falahati-Anbaran M, Stenøien HK, Pélabon C, Bolstad GH, Perez-Barrales R, Hansen TF, Armbruster WS. Development of microsatellite markers for the neotropical vine Dalechampia scandens (Euphorbiaceae). APPLICATIONS IN PLANT SCIENCES 2013; 1:apps1200492. [PMID: 25202553 PMCID: PMC4105026 DOI: 10.3732/apps.1200492] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 11/16/2012] [Indexed: 06/03/2023]
Abstract
PREMISE OF THE STUDY Microsatellite markers were developed to assess polymorphism and level of genetic diversity in four Mexican populations of the neotropical vine Dalechampia scandens (Euphorbiaceae). • METHODS AND RESULTS Thirty-seven microsatellite markers representing bi-, tri-, tetra-, and pentanucleotide microsatellite repeats were developed. In total, 166 alleles were identified across 54 individuals. The number of alleles varied from one to 11 with an average of 4.49 alleles per locus. All loci except one were highly polymorphic between populations, whereas considerably less variation was detected within populations for most loci. The average observed and expected heterozygosities across study populations ranged from 0 to 0.63 and 0 to 0.59, respectively, for individual loci, and a deviation from Hardy-Weinberg equilibrium was observed for most loci. • CONCLUSIONS The developed markers may be useful for studying genetic structure, parentage analysis, mapping, phylogeography, and cross-amplification in other closely related species of Dalechampia.
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Affiliation(s)
- Mohsen Falahati-Anbaran
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Hans K. Stenøien
- Museum of Natural History and Archaeology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Christophe Pélabon
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Geir H. Bolstad
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
| | - Rocio Perez-Barrales
- Plant Biology and Ecology Department, University of Seville, 41080 Seville, Spain
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
| | - Thomas F. Hansen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1066, N-0316 Oslo, Norway
| | - W. Scott Armbruster
- Department of Biology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
- School of Biological Sciences, University of Portsmouth, Portsmouth PO1 2DY, United Kingdom
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775 USA
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Joy JB. Symbiosis catalyses niche expansion and diversification. Proc Biol Sci 2013; 280:20122820. [PMID: 23390106 PMCID: PMC3574373 DOI: 10.1098/rspb.2012.2820] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 01/11/2013] [Indexed: 11/12/2022] Open
Abstract
Interactions between species are important catalysts of the evolutionary processes that generate the remarkable diversity of life. Symbioses, conspicuous and inherently interesting forms of species interaction, are pervasive throughout the tree of life. However, nearly all studies of the impact of species interactions on diversification have concentrated on competition and predation leaving unclear the importance of symbiotic interaction. Here, I show that, as predicted by evolutionary theories of symbiosis and diversification, multiple origins of a key innovation, symbiosis between gall-inducing insects and fungi, catalysed both expansion in resource use (niche expansion) and diversification. Symbiotic lineages have undergone a more than sevenfold expansion in the range of host-plant taxa they use relative to lineages without such fungal symbionts, as defined by the genetic distance between host plants. Furthermore, symbiotic gall-inducing insects are more than 17 times as diverse as their non-symbiotic relatives. These results demonstrate that the evolution of symbiotic interaction leads to niche expansion, which in turn catalyses diversification.
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Affiliation(s)
- Jeffrey B Joy
- Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A 1S6.
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Armbruster WS, Lee J, Edwards ME, Baldwin BG. FLORAL PAEDOMORPHY LEADS TO SECONDARY SPECIALIZATION IN POLLINATION OF MADAGASCARDALECHAMPIA(EUPHORBIACEAE). Evolution 2012; 67:1196-203. [DOI: 10.1111/evo.12002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Guillaume F, Otto SP. Gene functional trade-offs and the evolution of pleiotropy. Genetics 2012; 192:1389-409. [PMID: 22982578 PMCID: PMC3512146 DOI: 10.1534/genetics.112.143214] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/04/2012] [Indexed: 01/05/2023] Open
Abstract
Pleiotropy is the property of genes affecting multiple functions or characters of an organism. Genes vary widely in their degree of pleiotropy, but this variation is often considered a by-product of their evolutionary history. We present a functional theory of how pleiotropy may itself evolve. We consider genes that contribute to two functions, where contributing more to one function detracts from allocation to the second function. We show that whether genes become pleiotropic or specialize on a single function depends on the nature of trade-offs as gene activities contribute to different traits and on how the functionality of these traits affects fitness. In general, when a gene product can perform well at two functions, it evolves to do so, but not when pleiotropy would greatly disrupt each function. Consequently, reduced pleiotropy should often evolve, with genes specializing on the trait that is currently more important to fitness. Even when pleiotropy does evolve, not all genes are expected to become equally pleiotropic; genes with higher levels of expression are more likely to evolve greater pleiotropy. For the case of gene duplicates, we find that perfect subfunctionalization evolves only under stringent conditions. More often, duplicates are expected to maintain a certain degree of functional redundancy, with the gene contributing more to trait functionality evolving the highest degree of pleiotropy. Gene product interactions can facilitate subfunctionalization, but whether they do so depends on the curvature of the fitness surface. Finally, we find that stochastic gene expression favors pleiotropy by selecting for robustness in fitness components.
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Affiliation(s)
- Frédéric Guillaume
- Theoretical Biology, Institute of Integrative Biology, Eidgenössiche Technische Hochschule Zürich, CH-8092 Zürich, Switzerland.
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Vanhoenacker D, Ågren J, Ehrlén J. Non-linear relationship between intensity of plant-animal interactions and selection strength. Ecol Lett 2012; 16:198-205. [DOI: 10.1111/ele.12029] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Revised: 07/18/2012] [Accepted: 10/14/2012] [Indexed: 11/27/2022]
Affiliation(s)
| | - Jon Ågren
- Department of Plant Ecology and Evolution; Evolutionary Biology Centre; Uppsala University; Norbyvägen 18 D; SE; 752 36; Uppsala; Sweden
| | - Johan Ehrlén
- Department of Botany; Stockholm University; SE; 106 91; Stockholm; Sweden
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Adler LS, Seifert MG, Wink M, Morse GE. Reliance on pollinators predicts defensive chemistry across tobacco species. Ecol Lett 2012; 15:1140-8. [PMID: 22834564 DOI: 10.1111/j.1461-0248.2012.01838.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/13/2012] [Accepted: 06/26/2012] [Indexed: 11/27/2022]
Abstract
Defensive traits are typically studied in the context of avoiding antagonists, but may also mediate key interactions with mutualists. Plant chemical defences occur in flowers, suggesting pollinators may be agents of selection on defence. We hypothesised that floral defences would deter pollinators, and therefore, pollinators would select for lower defences in outcrossing than self-pollinating species. We measured pollinator reliance and alkaloid levels in 32 greenhouse-grown Nicotiana species. Using a comparative phylogenetic approach, we found significantly lower nectar, floral and leaf nicotine concentrations in outcrossing than selfing species, with a 15-fold decrease in leaf nicotine levels. Nicotine concentrations were positively correlated across tissues, suggesting that selection against floral defences could constrain the evolution of leaf defences. Thus, pollinators could shape the evolution not only of floral defences but also of defences in other tissues where herbivores have traditionally been considered the dominant agent of selection.
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Affiliation(s)
- Lynn S Adler
- Department of Plant, Soil and Insect Science, University of Massachusetts, Amherst, MA 01003, USA.
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48
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Valente LM, Manning JC, Goldblatt P, Vargas P. Did Pollination Shifts Drive Diversification in Southern African Gladiolus? Evaluating the Model of Pollinator-Driven Speciation. Am Nat 2012; 180:83-98. [DOI: 10.1086/666003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Ibanez S, Gallet C, Després L. Plant insecticidal toxins in ecological networks. Toxins (Basel) 2012; 4:228-43. [PMID: 22606374 PMCID: PMC3347001 DOI: 10.3390/toxins4040228] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 03/21/2012] [Accepted: 03/26/2012] [Indexed: 11/16/2022] Open
Abstract
Plant secondary metabolites play a key role in plant-insect interactions, whether constitutive or induced, C- or N-based. Anti-herbivore defences against insects can act as repellents, deterrents, growth inhibitors or cause direct mortality. In turn, insects have evolved a variety of strategies to act against plant toxins, e.g., avoidance, excretion, sequestration and degradation of the toxin, eventually leading to a co-evolutionary arms race between insects and plants and to co-diversification. Anti-herbivore defences also negatively impact mutualistic partners, possibly leading to an ecological cost of toxin production. However, in other cases toxins can also be used by plants involved in mutualistic interactions to exclude inadequate partners and to modify the cost/benefit ratio of mutualism to their advantage. When considering the whole community, toxins have an effect at many trophic levels. Aposematic insects sequester toxins to defend themselves against predators. Depending on the ecological context, toxins can either increase insects’ vulnerability to parasitoids and entomopathogens or protect them, eventually leading to self-medication. We conclude that studying the community-level impacts of plant toxins can provide new insights into the synthesis between community and evolutionary ecology.
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Affiliation(s)
- Sébastien Ibanez
- Swiss Federal Research Institute WSL, Community Ecology Unit, via Belsoggiorno 22, 6500 Bellinzona, Switzerland;
| | - Christiane Gallet
- Laboratoire d’Ecologie Alpine UMR CNRS 5553 Université de Savoie F-73376, Le Bourget-du-lac, France;
| | - Laurence Després
- Laboratoire d’Ecologie Alpine UMR CNRS 5553 Université Joseph Fourier B.P.53, 38041 Grenoble CEDEX 9, France
- Author to whom correspondence should be addressed; ; Tel.: +33-476635699; Fax: +33-476517942
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50
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Rajakumar R, San Mauro D, Dijkstra MB, Huang MH, Wheeler DE, Hiou-Tim F, Khila A, Cournoyea M, Abouheif E. Ancestral developmental potential facilitates parallel evolution in ants. Science 2012; 335:79-82. [PMID: 22223805 DOI: 10.1126/science.1211451] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Complex worker caste systems have contributed to the evolutionary success of advanced ant societies; however, little is known about the developmental processes underlying their origin and evolution. We combined hormonal manipulation, gene expression, and phylogenetic analyses with field observations to understand how novel worker subcastes evolve. We uncovered an ancestral developmental potential to produce a "supersoldier" subcaste that has been actualized at least two times independently in the hyperdiverse ant genus Pheidole. This potential has been retained and can be environmentally induced throughout the genus. Therefore, the retention and induction of this potential have facilitated the parallel evolution of supersoldiers through a process known as genetic accommodation. The recurrent induction of ancestral developmental potential may facilitate the adaptive and parallel evolution of phenotypes.
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Affiliation(s)
- Rajendhran Rajakumar
- Department of Biology, McGill University, 1205 Avenue Dr. Penfield, Montreal, Quebec, Canada, H3A 1B1
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