1
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Drager KI, Rivera MD, Gibson JC, Ruzi SA, Hanisch PE, Achury R, Suarez AV. Testing the predictive value of functional traits in diverse ant communities. Ecol Evol 2023; 13:e10000. [PMID: 37091559 PMCID: PMC10115899 DOI: 10.1002/ece3.10000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 03/22/2023] [Accepted: 03/24/2023] [Indexed: 04/25/2023] Open
Abstract
Associating morphological features with ecological traits is essential for understanding the connection between organisms and their roles in the environment. If applied successfully, functional trait approaches link form and function in an organism. However, functional trait data not associated with natural history information provide an incomplete picture of an organism's role in the ecosystem. Using data on the relative trophic position of 592 ant (Formicidae) samples comprising 393 species from 11 subfamilies and 19 widely distributed communities, we tested the extent to which commonly used functional proxies (i.e., morphometric traits) predict diet/trophic position as estimated from stable isotopes (δ15N). We chose ants as a group due to their ubiquity and abundance, as well as the wealth of available data on species traits and trophic levels. We measured 12 traits that have previously been identified as functionally significant, and corrected trait values for size and evolutionary history by using phylogenetically corrected trait residuals. Estimated trophic positions varied from 0.9 to 4.8 or roughly 4 trophic levels. Morphological data spanned nearly the entire size range seen in ants from the smallest (e.g., Strumigenys mitis total length 1.1 mm) to the largest species (e.g., Dinoponera australis total length 28.3 mm). We found overall body size, relative eye position, and scape length to be informative for predicting diet/trophic position in these communities, albeit with relatively weak predictive values. Specifically, trophic position was negatively correlated with body size and positively correlated with sensory traits (higher eye position and scape length). Our results suggest that functional trait-based approaches can be informative but should be used with caution unless clear links between form and function have been established.
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Affiliation(s)
- Kim I. Drager
- Department of Evolution, Ecology and BehaviorUniversity of Illinois505 S. Goodwin Ave. 515 Morrill HallUrbanaIllinois61801USA
| | - Michael D. Rivera
- Program in Ecology, Evolution and Conservation BiologyUniversity of Illinois505 S. Goodwin Ave. 515 Morrill HallUrbanaIllinois61801USA
| | - Joshua C. Gibson
- Department of EntomologyUniversity of Illinois505 S. Goodwin Ave. 320 Morrill HallUrbanaIllinois61801USA
- Beckman Institute for Advanced Science and TechnologyUniversity of Illinois at Urbana‐Champaign405 N. Mathews AveUrbanaIllinois61801USA
| | - Selina A. Ruzi
- Department of Applied EcologyNorth Carolina State University115 David Clark Labs, 100 Eugene Brooks AvenueRaleighNorth Carolina27695USA
| | - Priscila E. Hanisch
- Department of Animal Ecology and Tropical BiologyBiocenterUniversity of WürzburgAm Hubland 97074WürzburgGermany
- Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” MACN‐CONICETBuenos AiresArgentina
| | - Rafael Achury
- Department of EntomologyUniversity of Illinois505 S. Goodwin Ave. 320 Morrill HallUrbanaIllinois61801USA
- Terrestrial Ecology Research GroupTechnical University of MunichHans‐Carl‐von‐Carlowitz‐Platz 2Freising85354Germany
| | - Andrew V. Suarez
- Department of Evolution, Ecology and BehaviorUniversity of Illinois505 S. Goodwin Ave. 515 Morrill HallUrbanaIllinois61801USA
- Program in Ecology, Evolution and Conservation BiologyUniversity of Illinois505 S. Goodwin Ave. 515 Morrill HallUrbanaIllinois61801USA
- Department of EntomologyUniversity of Illinois505 S. Goodwin Ave. 320 Morrill HallUrbanaIllinois61801USA
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2
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Baratelli E, Tillberg C, Suarez A, Menke S, Naughton I, Holway D. Variation in Argentine ant (Linepithema humile) trophic position as a function of time. Biol Invasions 2022. [DOI: 10.1007/s10530-022-02898-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Roeder KA, Benson BR, Weiser MD, Kaspari M. Testing the role of body size and litter depth on invertebrate diversity across six forests in North America. Ecology 2021; 103:e03601. [PMID: 34820828 DOI: 10.1002/ecy.3601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/01/2021] [Accepted: 11/16/2021] [Indexed: 11/06/2022]
Abstract
Ecologists search for rules by which traits dictate the abundance and distribution of species. Here we search for rules that apply across three common taxa of litter invertebrates in six North American forests from Panama to Oregon. We use image analysis to quantify the abundance and body size distributions of mites, springtails, and spiders in 21 1-m2 plots per forest. We contrast three hypotheses: two of which focus on trait-abundance relationships and a third linking abundance to species richness. Despite three orders of magnitude variation in size, the predicted negative relationship between mean body size and abundance per area occurred in only 18% of cases, never for large bodied taxa like spiders. We likewise found only 18% of tests supported our prediction that increasing litter depth allows for high abundance; two-thirds of which occurred at a single deciduous forest in Massachusetts. In contrast, invertebrate abundance constrained species richness 76% of the time. Our results suggest that body size and habitat volume in brown food webs are rarely good predictors of variation in abundance, but that variation in diversity is generally well predicted by abundance.
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Affiliation(s)
- Karl A Roeder
- USDA, Agricultural Research Service, North Central Agricultural Research Laboratory, Brookings, South Dakota, 57006, USA.,Department of Biology, Geographical Ecology Group, University of Oklahoma, Norman, Oklahoma, 73019, USA
| | - Brittany R Benson
- Department of Biology, Geographical Ecology Group, University of Oklahoma, Norman, Oklahoma, 73019, USA.,Ecology Research Group, Faculty of Biosciences and Aquaculture, Nord University, Steinkjer, 7729, Norway
| | - Michael D Weiser
- Department of Biology, Geographical Ecology Group, University of Oklahoma, Norman, Oklahoma, 73019, USA
| | - Michael Kaspari
- Department of Biology, Geographical Ecology Group, University of Oklahoma, Norman, Oklahoma, 73019, USA
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4
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Sugar is an ant’s best friend? Testing food web theory predictions about trophic position and abundance in an invasive ant (Nylanderia fulva). Biol Invasions 2021. [DOI: 10.1007/s10530-021-02627-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Balzani P, Vizzini S, Frizzi F, Masoni A, Lessard J, Bernasconi C, Francoeur A, Ibarra‐Isassi J, Brassard F, Cherix D, Santini G. Plasticity in the trophic niche of an invasive ant explains establishment success and long‐term coexistence. OIKOS 2021. [DOI: 10.1111/oik.08217] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Paride Balzani
- Dept of Biology, Univ. of Florence Sesto Fiorentino Italy
| | - Salvatrice Vizzini
- Dept of Earth and Marine Sciences, Univ. of Palermo, CoNISMa Palermo Italy
- CoNISMa, Consorzio Nazionale Interuniversitario per le Scienze del Mare Roma Italy
| | - Filippo Frizzi
- Dept of Biology, Univ. of Florence Sesto Fiorentino Italy
| | - Alberto Masoni
- Dept of Biology, Univ. of Florence Sesto Fiorentino Italy
| | | | | | - André Francoeur
- Dept of Biology, Univ. of Quebec at Chicoutimi Chicoutimi QC Canada
| | | | | | - Daniel Cherix
- Dept of Ecology and Evolution, Univ. of Lausanne Lausanne Switzerland
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6
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Probert AF, Ward DF, Beggs JR, Bury SJ, Hermans SM, Lear G, Stanley MC. High Dietary Niche Overlap Between Non-native and Native Ant Species in Natural Ecosystems. ENVIRONMENTAL ENTOMOLOGY 2021; 50:86-96. [PMID: 33269804 DOI: 10.1093/ee/nvaa133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Indexed: 06/12/2023]
Abstract
Ants represent a highly diverse and ecologically important group of insects found in almost all terrestrial ecosystems. A subset of ant species have been widely transported around the globe and invade many natural ecosystems, often out-competing native counterparts and causing varying impacts on recipient ecosystems. Decisions to control non-native ant populations require an understanding of their interactions and related impacts on native communities. We employed stable isotope analysis and metabarcoding techniques to identify potential dietary niche overlap and identify gut contents of 10 ant species found in natural ecosystems in Aotearoa New Zealand. Additionally, we looked at co-occurrence to identify potential competitive interactions among native and non-native ant species. Ants fed mainly across two trophic levels, with high dietary overlap. Relative to other ant species sampled, two non-native ant species, Linepithema humile and Technomyrmex jocosus, were found to feed at the lowest trophic level. The largest isotopic niche overlap was observed between the native Monomorium antarcticum and the invasive Ochetellus glaber, with analyses revealing a negative co-occurrence pattern. Sequence data of ant gut content identified 51 molecular operational taxonomic units, representing 22 orders and 34 families, and primarily consisting of arthropod DNA. Although we generally found high dietary overlap among species, negative occurrence between a dominant, non-native species and a ubiquitous native species indicates that species-specific interactions could be negatively impacting native ecosystems. Our research progresses and informs the currently limited knowledge around establishing protocols for metabarcoding to investigate ant diet and interactions between native and non-native ant species.
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Affiliation(s)
- Anna F Probert
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Department of Biology, University of Fribourg, Ch. Du Musée, Fribourg, Switzerland
| | - Darren F Ward
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
- Manaaki Whenua - Landcare Research, Auckland, New Zealand
| | - Jacqueline R Beggs
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Sarah J Bury
- National Institute of Water & Atmospheric Science (NIWA), 301 Evans Bay Parade, Hataitai, Wellington, New Zealand
| | - Syrie M Hermans
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Gavin Lear
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Margaret C Stanley
- Centre for Biodiversity and Biosecurity, School of Biological Sciences, University of Auckland, Auckland, New Zealand
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7
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Seko Y, Hashimoto K, Koba K, Hayasaka D, Sawahata T. Intraspecific differences in the invasion success of the Argentine ant Linepithema humile Mayr are associated with diet breadth. Sci Rep 2021; 11:2874. [PMID: 33536543 PMCID: PMC7859199 DOI: 10.1038/s41598-021-82464-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/20/2021] [Indexed: 01/30/2023] Open
Abstract
The Argentine ant, Linepithema humile Mayr, has spread to almost all continents. In each introduced region, L. humile often forms a single large colony (supercolony), the members of which share the haplotype "LH1", despite the presence of other supercolonies with different genetic structures. However, the mechanisms underlying the successful invasion of LH1 ants are unclear. Here, we examined whether diet breadth differs between more successful (LH1) and less successful (LH2, LH3, LH4) L. humile supercolonies in Japan to better understand the processes responsible for invasion success. The standard ellipse areas (SEAs) of δ13C and δ15N and their ranges (CR and NR) were used as diet breadth indices. The SEAs of LH1 were much larger than those of the less successful supercolonies despite no differences in the baseline SEAs of arthropods within the supercolony habitats, indicating that the invasion success of a supercolony is associated with its diet breadth. Furthermore, LH1 had a broader CR than the other supercolonies, suggesting that which might be derived from superior resource exploitation ability. Our study highlights the importance of focusing on intraspecific differences in diet breadth among supercolonies when assessing organisms that can potentially invade and become dominant in new habitats.
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Affiliation(s)
- Yugo Seko
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara, 631-8505, Japan.
| | - Koya Hashimoto
- Faculty of Agriculture, Kindai University, Nakamachi 3327-204, Nara, 631-8505, Japan
- National Institute for Environmental Studies (NIES), Onogawa 16-2, Tsukuba, Ibaraki, 305-8506, Japan
| | - Keisuke Koba
- Center for Ecological Research (CER), Kyoto University, Hirano 2-509-3, Otsu, Shiga, 520-2113, Japan
| | - Daisuke Hayasaka
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara, 631-8505, Japan.
| | - Takuo Sawahata
- Graduate School of Agriculture, Kindai University, Nakamachi 3327-204, Nara, 631-8505, Japan
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8
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Helms JA, Roeder KA, Ijelu SE, Ratcliff I, Haddad NM. Bioenergy landscapes drive trophic shifts in generalist ants. J Anim Ecol 2020; 90:738-750. [PMID: 33314089 DOI: 10.1111/1365-2656.13407] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/12/2020] [Indexed: 11/28/2022]
Abstract
Changes in trophic niche-the pathways through which an organism obtains energy and nutrients-are a fundamental way in which organisms respond to environmental conditions. But the capacity for species to alter their trophic niches in response to global change, and the ways they do so when able, remain largely unknown. Here we examine food webs in three long-term and large-scale experiments to test how resource availability and nutritional requirements interact to determine an organism's trophic niche in the context of one of the largest global trends in land use-the rise in bioenergy production. We use carbon and nitrogen stable isotope analyses to characterize arthropod food webs across three biofuel crops representing a gradient in plant resource richness (corn monocultures, fields dominated by native switchgrass and restored prairie), and to quantify changes in the trophic niche of a widespread generalist ant species across habitats. In doing so, we measure the effects of basal resource richness on food chain length, niche breadth and trophic position. We frame our results in the context of two hypotheses that explain variation in trophic niche-the niche variation hypothesis which emphasizes the importance of resource diversity and ecological opportunity, and the optimal diet hypothesis which emphasizes dietary constraints and the availability of optimal resources. Increasing plant richness lengthened food chains by 10%-20% compared to monocultures. Niche breadths of generalist ants did not vary with resource richness, suggesting they were limited by optimal diet requirements and constraints rather than by ecological opportunity. The ants instead responded to changes in plant richness by shifting their estimated trophic position. In resource-poor monocultures, the ants were top predators, sharing a trophic position with predatory spiders. In resource-rich environments, in contrast, the ants were omnivores, relying on a mix of animal prey and plant-based resources. In addition to highlighting novel ecosystem impacts of alternate bioenergy landscapes, our results suggest that niche breadth and trophic diversification depend more on the presence of optimal resources than on ecological opportunity alone.
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Affiliation(s)
- Jackson A Helms
- Kellogg Biological Station, Department of Integrative Biology, Michigan State University, Hickory Corners, MI, USA
| | - Karl A Roeder
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | | | | | - Nick M Haddad
- Kellogg Biological Station, Department of Integrative Biology, Michigan State University, Hickory Corners, MI, USA
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9
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Pringle RM, Hutchinson MC. Resolving Food-Web Structure. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-110218-024908] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Food webs are a major focus and organizing theme of ecology, but the data used to assemble them are deficient. Early debates over food-web data focused on taxonomic resolution and completeness, lack of which had produced spurious inferences. Recent data are widely believed to be much better and are used extensively in theoretical and meta-analytic research on network ecology. Confidence in these data rests on the assumptions ( a) that empiricists correctly identified consumers and their foods and ( b) that sampling methods were adequate to detect a near-comprehensive fraction of the trophic interactions between species. Abundant evidence indicates that these assumptions are often invalid, suggesting that most topological food-web data may remain unreliable for inferences about network structure and underlying ecological and evolutionary processes. Morphologically cryptic species are ubiquitous across taxa and regions, and many trophic interactions routinely evade detection by conventional methods. Molecular methods have diagnosed the severity of these problems and are a necessary part of the cure.
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Affiliation(s)
- Robert M. Pringle
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Matthew C. Hutchinson
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA
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10
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Schmitt L, Aponte‐Rolón B, Perfecto I. Evaluating community effects of a Keystone Ant,
Azteca sericeasur,
on
Inga micheliana
leaf litter decomposition in a shaded coffee agro‐ecosystem. Biotropica 2020. [DOI: 10.1111/btp.12833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Lauren Schmitt
- School for Environment and Sustainability University of Michigan Ann Arbor Michigan USA
| | - Bolívar Aponte‐Rolón
- Department of Ecology and Evolutionary Biology Tulane University New Orleans Louisiana USA
| | - Ivette Perfecto
- School for Environment and Sustainability University of Michigan Ann Arbor Michigan USA
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11
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Reproductive physiology corresponds to adult nutrition and task performance in a Neotropical paper wasp: a test of dominance-nutrition hypothesis predictions. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02898-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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12
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Tsang TPN, Guénard B, Bonebrake TC. Omnivorous ants are less carnivorous and more protein-limited in exotic plantations. J Anim Ecol 2020; 89:1941-1951. [PMID: 32379899 DOI: 10.1111/1365-2656.13249] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 04/27/2020] [Indexed: 11/28/2022]
Abstract
Diets of species are crucial in determining how they influence food webs and community structures, and how their populations are regulated by different bottom-up processes. Omnivores are able to adjust their diet flexibly according to environmental conditions, such that their impacts on food webs and communities, and the macronutrients constraining their population, can be plastic. In particular, omnivore diets are known to be influenced by prey availability, which exhibits high spatial and temporal variation. To examine the plasticity of diet and macronutrient limitation in omnivores, we compared trophic positions, macronutrient preferences and food exploitation rates of omnivorous ants in invertebrate-rich (secondary forests) and invertebrate-poor (Lophostemon confertus plantations) habitats. We hypothesized that omnivorous ants would have lower trophic positions, enhanced protein limitation and reduced food exploitation rates in L. confertus plantations relative to secondary forests. We performed cafeteria experiments to examine changes in macronutrient limitation and food exploitation rates. We also sampled ants and conducted stable isotope analyses to investigate dietary shifts between these habitats. We found that conspecific ants were less carnivorous and had higher preferences for protein-rich food in L. confertus plantations compared to secondary forests. However, ant assemblages did not exhibit increased preferences for protein-rich food in L. confertus plantations. At the species-level, food exploitation rates varied idiosyncratically between habitats. At the assemblage-level, food exploitation rates were reduced in L. confertus plantations. Our results reveal that plantation establishments alter the diet and foraging behaviour of omnivorous ants. Such changes suggest that omnivorous ants in plantations will have reduced top-down impacts on prey communities but also see an increased importance of protein as a bottom-up force in constraining omnivore population sizes.
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Affiliation(s)
- Toby P N Tsang
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Benoit Guénard
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong SAR, People's Republic of China
| | - Timothy C Bonebrake
- School of Biological Sciences, Faculty of Science, The University of Hong Kong, Hong Kong SAR, People's Republic of China
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13
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Roeder KA, Prather RM, Paraskevopoulos AW, Roeder DV. The Economics of Optimal Foraging by the Red Imported Fire Ant. ENVIRONMENTAL ENTOMOLOGY 2020; 49:304-311. [PMID: 32144932 DOI: 10.1093/ee/nvaa016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Indexed: 05/24/2023]
Abstract
For social organisms, foraging is often a complicated behavior where tasks are divided among numerous individuals. Here, we ask how one species, the red imported fire ant (Solenopsis invicta Buren) (Hymenoptera: Formicidae), collectively manages this behavior. We tested the Diminishing Returns Hypothesis, which posits that for social insects 1) foraging investment levels increase until diminishing gains result in a decelerating slope of return and 2) the level of investment is a function of the size of the collective group. We compared how different metrics of foraging (e.g., number of foragers, mass of foragers, and body size of foragers) are correlated and how these metrics change over time. We then tested the prediction that as fire ant colonies increase in size, both discovery time and the inflection point (i.e., the time point where colonial investment toward resources slows) should decrease while a colony's maximum foraging mass should increase. In congruence with our predictions, we found that fire ants recruited en masse toward baits, allocating 486 workers and 148 mg of biomass, on average, after 60 min: amounts that were not different 30 min prior. There was incredible variation across colonies with discovery time, the inflection point, and the maximum biomass of foragers all being significantly correlated with colony size. We suggest that biomass is a solid indicator of how social taxa invest their workforce toward resources and hypothesize ways that invasive fire ants are able to leverage their enormous workforce to dominate novel ecosystems by comparing their foraging and colony mass with co-occurring native species.
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Affiliation(s)
- Karl A Roeder
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL
- Department of Biology, University of Oklahoma, Norman, OK
| | | | | | - Diane V Roeder
- Department of Agriculture, Biology and Health Sciences, Cameron University, Lawton, OK
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14
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Welti EAR, Prather RM, Sanders NJ, de Beurs KM, Kaspari M. Bottom-up when it is not top-down: Predators and plants control biomass of grassland arthropods. J Anim Ecol 2020; 89:1286-1294. [PMID: 32115723 DOI: 10.1111/1365-2656.13191] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 12/20/2019] [Indexed: 11/30/2022]
Abstract
We investigate where bottom-up and top-down control regulates ecological communities as a mechanism linking ecological gradients to the geography of consumer abundance and biomass. We use standardized surveys of 54 North American grasslands to test alternate hypotheses predicting 100-fold shifts in the biomass of four common grassland arthropod taxa-Auchenorrhyncha, sucking herbivores, Acrididae, chewing herbivores, Tettigoniidae, omnivores, and Araneae, predators. Bottom-up models predict that consumer biomass tracks plant quantity (e.g. productivity and standing biomass) and quality (nutrient content) and that ectotherm access to food increases with temperature. Each of the focal trophic groups responded differently to these drivers: the biomass of sucking herbivores and omnivores increased with plant biomass; that of chewing herbivores tracked plant quality; and predator biomass did not depend on plant quality, plant quantity or temperature. The Exploitation Ecosystem Hypothesis is a top-down hypothesis that predicts a shift from resource limitation of herbivores when plant production is low, to predator limitation when plant production is high. In grasslands where spider biomass was low, herbivore biomass increased with plant biomass, whereas bottom-up structuring was not evident when spiders were abundant. Furthermore, neither predator biomass nor trophic position (via stable isotope analysis) increased with plant biomass, suggesting predators themselves are top-down limited. Stable isotope analysis revealed that trophic position of the chewing herbivore and omnivore increased significantly with plant biomass, suggesting these groups increased scavenging and meat consumption in grasslands with higher carbohydrate availability. Taken together, our snapshot sampling documents gradients of food web structure across 54 grasslands, consistent with multiple hypotheses of bottom-up and top-down regulation.
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Affiliation(s)
- Ellen A R Welti
- Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, OK, USA
| | - Rebecca M Prather
- Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, OK, USA
| | - Nathan J Sanders
- The Environmental Program, Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT, USA
| | - Kirsten M de Beurs
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, OK, USA
| | - Michael Kaspari
- Geographical Ecology Group, Department of Biology, University of Oklahoma, Norman, OK, USA
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15
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Durso AM, Smith GD, Hudson SB, French SS. Stoichiometric and stable isotope ratios of wild lizards in an urban landscape vary with reproduction, physiology, space and time. CONSERVATION PHYSIOLOGY 2020; 8:coaa001. [PMID: 32082575 PMCID: PMC7019090 DOI: 10.1093/conphys/coaa001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/13/2019] [Accepted: 01/08/2020] [Indexed: 06/10/2023]
Abstract
Spatial and temporal variation in stoichiometric and stable isotope ratios of animals contains ecological information that we are just beginning to understand. In both field and lab studies, stoichiometric or isotopic ratios are related to physiological mechanisms underlying nutrition or stress. Conservation and ecosystem ecology may be informed by isotopic data that can be rapidly and non-lethally collected from wild animals, especially where human activity leaves an isotopic signature (e.g. via introduction of chemical fertilizers, ornamental or other non-native plants or organic detritus). We examined spatial and temporal variation in stoichiometric and stable isotope ratios of the toes of Uta stansburiana (side-blotched lizards) living in urban and rural areas in and around St. George, Utah. We found substantial spatial and temporal variation as well as context-dependent co-variation with reproductive physiological parameters, although certain key predictions such as the relationship between δ15N and body condition were not supported. We suggest that landscape change through urbanization can have profound effects on wild animal physiology and that stoichiometric and stable isotope ratios can provide unique insights into the mechanisms underlying these processes.
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Affiliation(s)
- Andrew M Durso
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
- Department of Biological Sciences, Florida Gulf Coast University, 10501 FGCU Blvd S, Fort Myers, FL 33965 USA
| | - Geoffrey D Smith
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
- Biological Sciences Department, Dixie State University, 225 S. University Avenue, St. George, UT 84770 USA
| | - Spencer B Hudson
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
| | - Susannah S French
- Department of Biology and the Ecology Center, Utah State University, 5305 Old Main Hill, Logan UT 84321 USA
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16
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Functional Role of Extrafloral Nectar in Boreal Forest Ecosystems under Climate Change. FORESTS 2020. [DOI: 10.3390/f11010067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Carbohydrate-rich extrafloral nectar (EFN) is produced in nectaries on the leaves, stipules, and stems of plants and provides a significant energy source for ants and other plant mutualists outside of the flowering period. Our review of literature on EFN indicates that only a few forest plant species in cool boreal environments bear EFN-producing nectaries and that EFN production in many boreal and subarctic plant species is poorly studied. Boreal forest, the world’s largest land biome, is dominated by coniferous trees, which, like most gymnosperms, do not produce EFN. Notably, common deciduous tree species that can be dominant in boreal forest stands, such as Betula and Alnus species, do not produce EFN, while Prunus and Populus species are the most important EFN-producing tree species. EFN together with aphid honeydew is known to play a main role in shaping ant communities. Ants are considered to be keystone species in mixed and conifer-dominated boreal and mountain forests because they transfer a significant amount of carbon from the canopy to the soil. Our review suggests that in boreal forests aphid honeydew is a more important carbohydrate source for ants than in many warmer ecosystems and that EFN-bearing plant species might not have a competitive advantage against herbivores. However, this hypothesis needs to be tested in the future. Warming of northern ecosystems under climate change might drastically promote the invasion of many EFN-producing plants and the associated insect species that consume EFN as their major carbohydrate source. This may result in substantial changes in the diet preferences of ant communities, the preventative roles of ants against insect pest outbreaks, and the ecosystem services they provide. However, wood ants have adapted to using tree sap that leaks from bark cracks in spring, which may mitigate the effects of improved EFN availability.
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Kim T, Bartel S, Gratton C. Grassland harvesting alters ant community trophic structure: An isotopic study in tallgrass prairies. Ecol Evol 2019; 9:9815-9826. [PMID: 31534696 PMCID: PMC6745673 DOI: 10.1002/ece3.5523] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 05/20/2019] [Accepted: 07/01/2019] [Indexed: 11/11/2022] Open
Abstract
Disturbances have long been recognized as important forces for structuring natural communities but their effects on trophic structure are not well understood, particularly in terrestrial systems. This is in part because quantifying trophic linkages is a challenge, especially for small organisms with cryptic feeding behaviors such as insects, and often relies on conducting labor-intensive feeding trials or extensive observations in the field. In this study, we used stable isotopes of carbon and nitrogen to examine how disturbance (annual biomass harvesting) in tallgrass prairies affected the trophic position, trophic range, and niche space of ants, a widespread grassland consumer. We hypothesized that biomass harvest would remove important food and nesting resources of insects thus affecting ant feeding relationships and trophic structure. We found shifts in the feeding relationships inferred by isotopic signatures with harvest. In particular, these shifts suggest that ants within harvest sites utilized resources at lower trophic levels (possibly plant-based resources or herbivores), expanded trophic breadth, and occupied different niche spaces. Shifts in resource use following harvest could be due to harvest-mediated changes in both the plant and arthropod communities that might affect the strength of competition or alter plant nitrogen availability. Because shifts in resource use alter the flow of nutrients across the food web, disturbance effects on ants could have ecosystem-level consequences through nutrient cycling.
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Affiliation(s)
- Tania Kim
- Great Lakes Bioenergy Research CenterUniversity of Wisconsin MadisonMadisonWIUSA
| | - Savannah Bartel
- Department of Integrative BiologyUniversity of Wisconsin MadisonMadisonWIUSA
| | - Claudio Gratton
- Great Lakes Bioenergy Research CenterUniversity of Wisconsin MadisonMadisonWIUSA
- Department of EntomologyUniversity of Wisconsin MadisonMadisonWIUSA
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Wong MKL, Guénard B, Lewis OT. Trait-based ecology of terrestrial arthropods. Biol Rev Camb Philos Soc 2019; 94:999-1022. [PMID: 30548743 PMCID: PMC6849530 DOI: 10.1111/brv.12488] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 11/21/2018] [Accepted: 11/23/2018] [Indexed: 12/11/2022]
Abstract
In focusing on how organisms' generalizable functional properties (traits) interact mechanistically with environments across spatial scales and levels of biological organization, trait-based approaches provide a powerful framework for attaining synthesis, generality and prediction. Trait-based research has considerably improved understanding of the assembly, structure and functioning of plant communities. Further advances in ecology may be achieved by exploring the trait-environment relationships of non-sessile, heterotrophic organisms such as terrestrial arthropods, which are geographically ubiquitous, ecologically diverse, and often important functional components of ecosystems. Trait-based studies and trait databases have recently been compiled for groups such as ants, bees, beetles, butterflies, spiders and many others; however, the explicit justification, conceptual framework, and primary-evidence base for the burgeoning field of 'terrestrial arthropod trait-based ecology' have not been well established. Consequently, there is some confusion over the scope and relevance of this field, as well as a tendency for studies to overlook important assumptions of the trait-based approach. Here we aim to provide a broad and accessible overview of the trait-based ecology of terrestrial arthropods. We first define and illustrate foundational concepts in trait-based ecology with respect to terrestrial arthropods, and justify the application of trait-based approaches to the study of their ecology. Next, we review studies in community ecology where trait-based approaches have been used to elucidate how assembly processes for terrestrial arthropod communities are influenced by niche filtering along environmental gradients (e.g. climatic, structural, and land-use gradients) and by abiotic and biotic disturbances (e.g. fire, floods, and biological invasions). We also review studies in ecosystem ecology where trait-based approaches have been used to investigate biodiversity-ecosystem function relationships: how the functional diversity of arthropod communities relates to a host of ecosystem functions and services that they mediate, such as decomposition, pollination and predation. We then suggest how future work can address fundamental assumptions and limitations by investigating trait functionality and the effects of intraspecific variation, assessing the potential for sampling methods to bias the traits and trait values observed, and enhancing the quality and consolidation of trait information in databases. A roadmap to guide observational trait-based studies is also presented. Lastly, we highlight new areas where trait-based studies on terrestrial arthropods are well positioned to advance ecological understanding and application. These include examining the roles of competitive, non-competitive and (multi-)trophic interactions in shaping coexistence, and macro-scaling trait-environment relationships to explain and predict patterns in biodiversity and ecosystem functions across space and time. We hope this review will spur and guide future applications of the trait-based framework to advance ecological insights from the most diverse eukaryotic organisms on Earth.
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Affiliation(s)
- Mark K. L. Wong
- Department of ZoologyUniversity of OxfordOxford, OX1 3PSU.K.
| | - Benoit Guénard
- School of Biological SciencesThe University of Hong Kong, Kadoorie Biological Sciences BuildingHong KongSARChina
| | - Owen T. Lewis
- Department of ZoologyUniversity of OxfordOxford, OX1 3PSU.K.
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19
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Shik JZ, Rytter W, Arnan X, Michelsen A. Disentangling nutritional pathways linking leafcutter ants and their co-evolved fungal symbionts using stable isotopes. Ecology 2018; 99:1999-2009. [PMID: 30067862 PMCID: PMC6174977 DOI: 10.1002/ecy.2431] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 04/30/2018] [Accepted: 05/19/2018] [Indexed: 11/09/2022]
Abstract
Leafcutter ants are the ultimate insect superorganisms, with up to millions of physiologically specialized workers cooperating to cut and transport vegetation and then convert it into compost used to cultivate co-evolved fungi, domesticated over millions of years. We tested hypotheses about the nutrient-processing dynamics governing this functional integration, tracing 15 N- and 13 C-enriched substrates through colonies of the leafcutter ant Atta colombica. Our results highlight striking performance efficiencies, including rapid conversion (within 2 d) of harvested nutrients into edible fungal tissue (swollen hyphal tips called gongylidia) in the center of fungus gardens, while also highlighting that much of each colony's foraging effort resulted in substrate placed directly in the trash. We also find nutrient-specific processing dynamics both within and across layers of the fungus garden, and in ant consumers. Larvae exhibited higher overall levels of 15 N and 13 C enrichment than adult workers, supporting that the majority of fungal productivity is allocated to colony growth. Foragers assimilated 13 C-labeled glucose during its ingestion, but required several days to metabolically process ingested 15 N-labeled ammonium nitrate. This processing timeline helps resolve a 40-yr old hypothesis, that foragers (but apparently not gardeners or larvae) bypass their fungal crops to directly assimilate some of the nutrients they ingest outside the nest. Tracing these nutritional pathways with stable isotopes helps visualize how physiological integration within symbiotic networks gives rise to the ecologically dominant herbivory of leafcutter ants in habitats ranging from Argentina to the southern United States.
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Affiliation(s)
- Jonathan Z. Shik
- Centre for Social EvolutionDepartment of BiologyUniversity of CopenhagenUniversitetsparken 152100CopenhagenDenmark
- Smithsonian Tropical Research InstituteApartado0843‐03092BalboaAnconRepublic of Panama
| | - Winnie Rytter
- Centre for Social EvolutionDepartment of BiologyUniversity of CopenhagenUniversitetsparken 152100CopenhagenDenmark
| | - Xavier Arnan
- CREAFCerdanyola del VallèsES‐08193CatalunyaSpain
| | - Anders Michelsen
- Terrestrial Ecology SectionDepartment of BiologyUniversity of CopenhagenUniversitetsparken 152100CopenhagenDenmark
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Prather RM, Roeder KA, Sanders NJ, Kaspari M. Using metabolic and thermal ecology to predict temperature dependent ecosystem activity: a test with prairie ants. Ecology 2018; 99:2113-2121. [DOI: 10.1002/ecy.2445] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 05/22/2018] [Accepted: 06/18/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Rebecca M. Prather
- Department of Biology Graduate Program in Ecology and Evolutionary Biology University of Oklahoma Norman Oklahoma 73019 USA
| | - Karl A. Roeder
- Department of Biology Graduate Program in Ecology and Evolutionary Biology University of Oklahoma Norman Oklahoma 73019 USA
| | - Nathan J. Sanders
- Rubenstein School of Environment and Natural Resources University of Vermont Burlington Vermont 05405 USA
| | - Michael Kaspari
- Department of Biology Graduate Program in Ecology and Evolutionary Biology University of Oklahoma Norman Oklahoma 73019 USA
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21
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Roeder KA, Roeder DV, Kaspari M. Disturbance Mediates Homogenization of Above and Belowground Invertebrate Communities. ENVIRONMENTAL ENTOMOLOGY 2018; 47:545-550. [PMID: 29554242 DOI: 10.1093/ee/nvy022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Natural disturbances can occur stochastically with profound impacts on fauna and flora. Here we quantified the impact of a one in 100-yr flood on terrestrial invertebrate communities in south central Oklahoma. Before the flood, we observed 4,082 individuals from 92 species weighing a total of 18.61 g that belonged to compositionally different above or belowground communities. One year after the initial sampling period and 9 mo post-flood, we measured a 93% decrease in abundance, a 60% decrease in species richness, and a 64% decrease in biomass as well as increased compositional similarity between the above and belowground communities. Of the eight insect orders that were present before the flood, only the Coleoptera and Orthoptera increased immediately after the flood. Of these, only the Orthoptera remained at an elevated level across all post-flood sampling periods, specifically due to an increase in crickets (Orthoptera: Gryllidae). As we enter an era of global change, using natural perturbation experiments will improve our knowledge about the ecological processes that shape patterns of community assembly and biodiversity.
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Affiliation(s)
- Karl A Roeder
- Department of Biology, Graduate Program in Ecology and Evolutionary Biology, University of Oklahoma, Norman, OK
| | - Diane V Roeder
- Department of Agriculture, Biology and Health Sciences, Cameron University, Lawton, OK
| | - Michael Kaspari
- Department of Biology, Graduate Program in Ecology and Evolutionary Biology, University of Oklahoma, Norman, OK
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