1
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Species loss and nitrogen pollution alter litter decomposition dynamics in coastal salt marshes. Oecologia 2022; 200:479-490. [DOI: 10.1007/s00442-022-05273-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 10/04/2022] [Indexed: 11/06/2022]
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2
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Can prey occupancy act as a surrogate for mesopredator occupancy? A case study of ocelot (Leopardus pardalis). Mamm Biol 2022. [DOI: 10.1007/s42991-022-00232-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Carvalho RL, Anjos DV, Fagundes R, Luna P, Ribeiro SP. Similar topologies of individual‐based plant‐herbivorous networks in forest interior and anthropogenic edges. AUSTRAL ECOL 2021. [DOI: 10.1111/aec.13001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raquel L Carvalho
- Departamento de Biodiversidade Evolução e Meio Ambiente Universidade Federal de Ouro Preto Ouro Preto Minas GeraisC.P. 35400‐000Brazil
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Minas GeraisC.P. 38400‐902Brazil
| | - Diego V Anjos
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Minas GeraisC.P. 38400‐902Brazil
| | - Roberth Fagundes
- Universidade da Integração Internacional da Lusofonia Afro‐Brasileira Redenção CearáC.P. 62790‐000Brazil
| | - Pedro Luna
- Red de Ecoetología Instituto de Ecología AC Xalapa VeracruzC.P. 91070Mexico
| | - Sérvio Pontes Ribeiro
- Departamento de Biodiversidade Evolução e Meio Ambiente Universidade Federal de Ouro Preto Ouro Preto Minas GeraisC.P. 35400‐000Brazil
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4
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Smaller and Isolated Grassland Fragments Are Exposed to Stronger Seed and Insect Predation in Habitat Edges. FORESTS 2021. [DOI: 10.3390/f12010054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Habitat fragmentation threatens terrestrial arthropod biodiversity, and thereby also leads to alterations of ecosystem functioning and stability. Predation on insects and seeds by arthropods are two very important ecological functions because of their community-structuring effects. We addressed the effect of fragment connectivity, fragment size, and edge effect on insect and seed predation of arthropods. We studied 60 natural fragments of two grassland ecosystems in the same region (Hungarian Great Plain), 30 forest-steppes, and 30 burial mounds (kurgans). The size of fragments were in the range of 0.16–6.88 ha for forest-steppe and 0.01–0.44 ha for kurgan. We used 2400 sentinel arthropod preys (dummy caterpillars) and 4800 seeds in trays for the measurements. Attack marks on dummy caterpillars were used for predator identification and calculation of insect predation rates. In the case of seeds, predation rates were calculated as the number of missing or damaged seeds per total number of exposed seeds. Increasing connectivity played a role only in generally small kurgans, with a negative effect on insect and seed predation rates in the edges. In contrast, fragment size moderated edge effects on insect and seed predation rates in generally large forest-steppes. The difference between edges and centres was more pronounced in small than in large fragments. Our study emphasizes the important role of landscape and fragment-scale factors interacting with edge effect in shaping ecosystem functions in natural grassland fragments of modified landscapes. Managing functional landscapes to optimize the assessment of ecosystem functions and services needs a multispatial scale approach.
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5
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Anderson RM, Dallar NM, Pirtel NL, Connors CJ, Mickley J, Bagchi R, Singer MS. Bottom-Up and Top-Down Effects of Forest Fragmentation Differ Between Dietary Generalist and Specialist Caterpillars. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00452] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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6
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Wimp GM, Ries L, Lewis D, Murphy SM. Habitat edge responses of generalist predators are predicted by prey and structural resources. Ecology 2019; 100:e02662. [PMID: 31013545 DOI: 10.1002/ecy.2662] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 11/30/2018] [Accepted: 01/02/2019] [Indexed: 11/09/2022]
Abstract
Generalist predators are thought to be less vulnerable to habitat fragmentation because they use diverse resources across larger spatial scales than specialist predators. Thus, it has been suggested that generalist predators may respond positively to habitat edges or demonstrate no edge response, because they can potentially use prey resources equally well on both sides of the habitat edge. However, most predictions about generalist predator responses to the habitat edge are based solely on prey resources, without consideration of other potential drivers. For instance, structural resources are essential for some species to build webs to capture prey or to avoid intraguild predation and cannibalism. In this study, we used both prey and structural resources to predict the response of four predator functional groups (hunting spiders, web-building spiders, aerial predators, and epigeic predators that feed on the detrital/algal food web) to a habitat edge between two salt-marsh grasses (Spartina alterniflora and Spartina patens). We found that generalist predators largely demonstrated negative responses to the habitat edge and had distinct habitat associations. Positive edge responses were only observed in one functional group (hunting spiders), and this pattern was driven by the two most abundant species. Negative responses to the habitat edge were more common among taxa and were better explained by structural resources rather than prey resources in the two habitats. Although it is generally acknowledged that specialists decline in fragmented habitats, generalists are thought to be more resilient. However, our research demonstrates that even generalists have habitat structural or food resource requirements that may limit their resilience to habitat loss and fragmentation.
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Affiliation(s)
- Gina M Wimp
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Leslie Ries
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Danny Lewis
- Biology Department, Georgetown University, Washington, D.C., 20057, USA
| | - Shannon M Murphy
- Department of Biological Sciences, University of Denver, Denver, Colorado, 80208, USA
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7
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Bagchi R, Brown LM, Elphick CS, Wagner DL, Singer MS. Anthropogenic fragmentation of landscapes: mechanisms for eroding the specificity of plant-herbivore interactions. Oecologia 2018; 187:521-533. [PMID: 29560512 DOI: 10.1007/s00442-018-4115-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 03/11/2018] [Indexed: 11/26/2022]
Abstract
Reduced ecological specialization is an emerging, general pattern of ecological networks in fragmented landscapes. In plant-herbivore interactions, reductions in dietary specialization of herbivore communities are consistently associated with fragmented landscapes, but the causes remain poorly understood. We propose several hypothetical bottom-up and top-down mechanisms that may reduce the specificity of plant-herbivore interactions. These include empirically plausible applications and extensions of theory based on reduced habitat patch size and isolation (considered jointly), and habitat edge effects. Bottom-up effects in small, isolated habitat patches may limit availability of suitable hostplants, a constraint that increases with dietary specialization. Poor hostplant quality due to inbreeding in such fragments may especially disadvantage dietary specialist herbivores even when their hostplants are present. Size and isolation of habitat patches may change patterns of predation of herbivores, but whether such putative changes are associated with herbivore dietary specialization should depend on the mobility, size, and diet breadth of predators. Bottom-up edge effects may favor dietary generalist herbivores, yet top-down edge effects may favor dietary specialists owing to reduced predation. An increasingly supported edge effect is trophic ricochets generated by large grazers/browsers, which remove key hostplant species of specialist herbivores. We present empirical evidence that greater deer browsing in small forest fragments disproportionately reduces specialist abundances in lepidopteran assemblages in northeastern USA. Despite indirect evidence for these mechanisms, they have received scant direct testing with experimental approaches at a landscape scale. Identifying their relative contributions to reduced specificity of plant-herbivore interactions in fragmented landscapes is an important research goal.
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Affiliation(s)
- Robert Bagchi
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road Unit 3043, Storrs, CT, 06260-3043, USA.
| | - Leone M Brown
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road Unit 3043, Storrs, CT, 06260-3043, USA
| | - Chris S Elphick
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road Unit 3043, Storrs, CT, 06260-3043, USA
| | - David L Wagner
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road Unit 3043, Storrs, CT, 06260-3043, USA
| | - Michael S Singer
- Department of Biology, Wesleyan University, Middletown, CT, 06459, USA
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8
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9
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Hamm M, Drossel B. Habitat heterogeneity hypothesis and edge effects in model metacommunities. J Theor Biol 2017; 426:40-48. [PMID: 28529154 DOI: 10.1016/j.jtbi.2017.05.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/09/2017] [Accepted: 05/18/2017] [Indexed: 11/19/2022]
Abstract
Spatial heterogeneity is an inherent property of any living environment and is expected to favour biodiversity due to a broader niche space. Furthermore, edges between different habitats can provide additional possibilities for species coexistence. Using computer simulations, this study examines metacommunities consisting of several trophic levels in heterogeneous environments in order to explore the above hypotheses on a community level. We model heterogeneous landscapes by using two different sized resource pools and evaluate the combined effect of dispersal and heterogeneity on local and regional species diversity. This diversity is obtained by running population dynamics and evaluating the robustness (i.e., the fraction of surviving species). The main results for regional robustness are in agreement with the habitat heterogeneity hypothesis, as the largest robustness is found in heterogeneous systems with intermediate dispersal rates. This robustness is larger than in homogeneous systems with the same total amount of resources. We study the edge effect by arranging the two types of resources in two homogeneous blocks. Different edge responses in diversity are observed, depending on dispersal strength. Local robustness is highest for edge habitats that contain the smaller amount of resource in combination with intermediate dispersal. The results show that dispersal is relevant to correctly identify edge responses on community level.
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Affiliation(s)
- Michaela Hamm
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany.
| | - Barbara Drossel
- Institut für Festkörperphysik, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
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10
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Peralta G, Frost CM, Didham RK, Rand TA, Tylianakis JM. Non-random food-web assembly at habitat edges increases connectivity and functional redundancy. Ecology 2017; 98:995-1005. [PMID: 27859031 DOI: 10.1002/ecy.1656] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 10/03/2016] [Accepted: 10/28/2016] [Indexed: 01/30/2023]
Abstract
Habitat fragmentation dramatically alters the spatial configuration of landscapes, with the creation of artificial edges affecting community structure and dynamics. Despite this, it is not known how the different food webs in adjacent habitats assemble at their boundaries. Here we demonstrate that the composition and structure of herbivore-parasitoid food webs across edges between native and plantation forests are not randomly assembled from those of the adjacent communities. Rather, elevated proportions of abundant, interaction-generalist parasitoid species at habitat edges allowed considerable interaction rewiring, which led to higher linkage density and less modular networks, with higher parasitoid functional redundancy. This was despite high overlap in host composition between edges and interiors. We also provide testable hypotheses for how food webs may assemble between habitats with lower species overlap. In an increasingly fragmented world, non-random assembly of food webs at edges may increasingly affect community dynamics at the landscape level.
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Affiliation(s)
- Guadalupe Peralta
- School of Biological Sciences, University of Canterbury, Christchurch, 8140, New Zealand.,las Zonas Áridas, CONICET, CC 507, 5500, Mendoza, Argentina
| | - Carol M Frost
- School of Biological Sciences, University of Canterbury, Christchurch, 8140, New Zealand.,Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd, Umeå, Sweden
| | - Raphael K Didham
- School of Animal Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia.,CSIRO Land & Water, Centre for Environment and Life Sciences, Floreat, Western Australia, 6014, Australia
| | - Tatyana A Rand
- USDA-ARS Northern Plains Agricultural Research Laboratory, Sidney, Montana, 59270, USA
| | - Jason M Tylianakis
- School of Biological Sciences, University of Canterbury, Christchurch, 8140, New Zealand.,Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 7PY, UK
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11
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12
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Rielly-Carroll E, Freestone AL. Habitat fragmentation differentially affects trophic levels and alters behavior in a multi-trophic marine system. Oecologia 2016; 183:899-908. [PMID: 28000022 DOI: 10.1007/s00442-016-3791-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 11/30/2016] [Indexed: 11/28/2022]
Abstract
Seagrass, an important subtidal marine ecosystem, is being lost at a rate of 110 km2 year-1, leading to fragmented seagrass seascapes. Habitat fragmentation is predicted to affect trophic levels differently, with higher trophic levels being more sensitive, stressing the importance of a multi-trophic perspective. Utilizing the trophic relationship between the blue crab (Callinectes sapidus) and hard clam (Mercenaria mercenaria), where adult blue crabs prey on juvenile blue crabs, and juvenile blue crabs prey on small hard clams, we examined whether predation rates, abundance, and behavior of predators and prey differed between continuous and fragmented seagrass in a multi-trophic context at two sites in Barnegat Bay, NJ. We tested the hypothesis that fragmented habitats would differentially affect trophic levels within a tri-trophic system, and our results supported this hypothesis. Densities of adult blue crabs were higher in fragmented than continuous habitats. Densities of juvenile blue crabs, the primary predator of hard clams, were lower in fragmented habitats than continuous, potentially due to increased predation by adult blue crabs. Clams experienced lower predation and burrowed to a shallower depth in fragmented habitats than in continuous habitat, likely due in part to the low densities of juvenile blue crabs, their primary predator. Our results suggest that while trophic levels are differentially affected, the impact of habitat fragmentation may be stronger on intermediate rather than top trophic levels in some marine systems.
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Affiliation(s)
- Elizabeth Rielly-Carroll
- Department of Biology, Holy Family University, 9801 Frankford Avenue, Philadelphia, PA, 19114, USA.
| | - Amy L Freestone
- Department of Biology, Temple University, Philadelphia, PA, USA
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13
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Kelch NS, Neves FS, Fernandes GW, Wirth R. Mechanisms Driving Galling Success in a Fragmented Landscape: Synergy of Habitat and Top-Down Factors along Temperate Forest Edges. PLoS One 2016; 11:e0157448. [PMID: 27310599 PMCID: PMC4910982 DOI: 10.1371/journal.pone.0157448] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/31/2016] [Indexed: 11/24/2022] Open
Abstract
Edge effects play key roles in the anthropogenic transformation of forested ecosystems and their biota, and are therefore a prime field of contemporary fragmentation research. We present the first empirical study to address edge effects on the population level of a widespread galling herbivore in a temperate deciduous forest. By analyzing edge effects on abundance and trophic interactions of beech gall midge (Mikiola fagi Htg.), we found 30% higher gall abundance in the edge habitat as well as lower mortality rates due to decreased top-down control, especially by parasitoids. Two GLM models with similar explanatory power (58%) identified habitat specific traits (such as canopy closure and altitude) and parasitism as the best predictors of gall abundance. Further analyses revealed a crucial influence of light exposure (46%) on top-down control by the parasitoid complex. Guided by a conceptual framework synthesizing the key factors driving gall density, we conclude that forest edge proliferation of M. fagi is due to a complex interplay of abiotic changes and trophic control mechanisms. Most prominently, it is caused by the microclimatic regime in forest edges, acting alone or in synergistic concert with top-down pressure by parasitoids. Contrary to the prevailing notion that specialists are edge-sensitive, this turns M. fagi into a winner species in fragmented temperate beech forests. In view of the increasing proportion of edge habitats and the documented benefits from edge microclimate, we call for investigations exploring the pest status of this galling insect and the modulators of its biological control.
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Affiliation(s)
- Nina-S. Kelch
- Plant Ecology & Systematics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Frederico S. Neves
- Departamento de Biologia Geral, Instituto de Ciéncias Biológicas, Universidade Federal de Minas Gerais—UFMG, Belo Horizonte, Minas Gerais, Brazil
| | - G. Wilson Fernandes
- Departamento de Biologia Geral, Instituto de Ciéncias Biológicas, Universidade Federal de Minas Gerais—UFMG, Belo Horizonte, Minas Gerais, Brazil
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Rainer Wirth
- Plant Ecology & Systematics, University of Kaiserslautern, Kaiserslautern, Germany
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14
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Murphy SM, Battocletti AH, Tinghitella RM, Wimp GM, Ries L. Complex community and evolutionary responses to habitat fragmentation and habitat edges: what can we learn from insect science? CURRENT OPINION IN INSECT SCIENCE 2016; 14:61-65. [PMID: 27436648 DOI: 10.1016/j.cois.2016.01.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 05/28/2023]
Abstract
Habitat fragmentation is the primary factor leading to species extinction worldwide and understanding how species respond to habitat edges is critical for understanding the effects of fragmentation on insect diversity in both natural and managed landscapes. Most studies on insect responses to the habitat edge focus on bottom-up changes in resources. Only a few recent studies have examined multi-trophic responses to habitat edges; the results of these studies highlight the problem that we lack a conceptual framework to understand the complex results observed when a single species' response to an edge 'cascades' throughout the food web in ways that are currently not predictable. Recent research from insect systems suggests that habitat edge responses cascade both up and down multi-trophic foodwebs and these altered species interactions may affect evolutionary processes. Future studies that investigate the effects of habitat edges on both ecological and evolutionary dynamics can help to fill these knowledge gaps and we suggest that insects, with short generation times, present an ideal opportunity to do so.
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Affiliation(s)
- Shannon M Murphy
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA.
| | - Amy H Battocletti
- Biology Department, Georgetown University, Washington, D.C. 20057, USA
| | - Robin M Tinghitella
- Department of Biological Sciences, University of Denver, Denver, CO 80208, USA
| | - Gina M Wimp
- Biology Department, Georgetown University, Washington, D.C. 20057, USA
| | - Leslie Ries
- Biology Department, Georgetown University, Washington, D.C. 20057, USA
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15
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Hahn PG, Orrock JL. Spatial arrangement of canopy structure and land-use history alter the effect that herbivores have on plant growth. Ecosphere 2015. [DOI: 10.1890/es15-00036.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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16
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Peralta G, Frost CM, Didham RK, Varsani A, Tylianakis JM. Phylogenetic diversity and co-evolutionary signals among trophic levels change across a habitat edge. J Anim Ecol 2014; 84:364-72. [DOI: 10.1111/1365-2656.12296] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 09/19/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Guadalupe Peralta
- School of Biological Sciences; University of Canterbury; Private bag 4800 Christchurch 8140 New Zealand
| | - Carol M. Frost
- School of Biological Sciences; University of Canterbury; Private bag 4800 Christchurch 8140 New Zealand
| | - Raphael K. Didham
- School of Animal Biology; University of Western Australia; 35 Stirling Highway Crawley WA 6009 Australia
- CSIRO Ecosystem Sciences; Centre for Environment and Life Sciences; Underwood Ave Floreat WA 6014 Australia
| | - Arvind Varsani
- School of Biological Sciences; University of Canterbury; Private bag 4800 Christchurch 8140 New Zealand
- Biomolecular Interaction Centre; University of Canterbury; Private Bag 4800 Christchurch 8140 New Zealand
- Electron Microscope Unit; University of Cape Town; Rondebosch Cape Town 7701 South Africa
- Department of Plant Pathology and Emerging Pathogens Institute; University of Florida; PO Box 110680 Gainesville FL 32611-0680 USA
| | - Jason M. Tylianakis
- School of Biological Sciences; University of Canterbury; Private bag 4800 Christchurch 8140 New Zealand
- Department of Life Sciences; Imperial College London; Silwood Park Campus; Buckhurst Road Ascot Berkshire SL5 7PY UK
- Allan Wilson Centre for Molecular Ecology and Evolution; University of Canterbury; Private Bag 4800 Christchurch 8140 New Zealand
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17
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Martinson HM, Fagan WF. Trophic disruption: a meta-analysis of how habitat fragmentation affects resource consumption in terrestrial arthropod systems. Ecol Lett 2014; 17:1178-89. [PMID: 24866984 DOI: 10.1111/ele.12305] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 12/21/2013] [Accepted: 05/08/2014] [Indexed: 11/29/2022]
Abstract
Habitat fragmentation is a complex process that affects ecological systems in diverse ways, altering everything from population persistence to ecosystem function. Despite widespread recognition that habitat fragmentation can influence food web interactions, consensus on the factors underlying variation in the impacts of fragmentation across systems remains elusive. In this study, we conduct a systematic review and meta-analysis to quantify the effects of habitat fragmentation and spatial habitat structure on resource consumption in terrestrial arthropod food webs. Across 419 studies, we found a negative overall effect of fragmentation on resource consumption. Variation in effect size was extensive but predictable. Specifically, resource consumption was reduced on small, isolated habitat fragments, higher at patch edges, and neutral with respect to landscape-scale spatial variables. In general, resource consumption increased in fragmented settings for habitat generalist consumers but decreased for specialist consumers. Our study demonstrates widespread disruption of trophic interactions in fragmented habitats and describes variation among studies that is largely predictable based on the ecological traits of the interacting species. We highlight future prospects for understanding how changes in spatial habitat structure may influence trophic modules and food webs.
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Affiliation(s)
- Holly M Martinson
- Department of Entomology, University of Maryland, College Park, MD, 20742, USA
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18
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Schneider G, Krauss J, Steffan-Dewenter I. Predation rates on semi-natural grasslands depend on adjacent habitat type. Basic Appl Ecol 2013. [DOI: 10.1016/j.baae.2013.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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19
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Stoepler TM, Lill JT. Direct and indirect effects of light environment generate ecological trade-offs in herbivore performance and parasitism. Ecology 2013; 94:2299-310. [DOI: 10.1890/12-2068.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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20
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Blackwood CB, Smemo KA, Kershner MW, Feinstein LM, Valverde-Barrantes OJ. Decay of ecosystem differences and decoupling of tree community–soil environment relationships at ecotones. ECOL MONOGR 2013. [DOI: 10.1890/12-1513.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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21
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Fortin D, Buono PL, Fortin A, Courbin N, Tye Gingras C, Moorcroft PR, Courtois R, Dussault C. Movement responses of caribou to human-induced habitat edges lead to their aggregation near anthropogenic features. Am Nat 2013; 181:827-36. [PMID: 23669544 DOI: 10.1086/670243] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The assessment of disturbance effects on wildlife and resulting mitigation efforts are founded on edge-effect theory. According to the classical view, the abundance of animals affected by human disturbance should increase monotonically with distance from disturbed areas to reach a maximum at remote locations. Here we show that distance-dependent movement taxis can skew abundance distributions toward disturbed areas. We develop an advection-diffusion model based on basic movement behavior commonly observed in animal populations and parameterize the model from observations on radio-collared caribou in a boreal ecosystem. The model predicts maximum abundance at 3.7 km from cutovers and roads. Consistently, aerial surveys conducted over 161,920 km(2) showed that the relative probability of caribou occurrence displays nonmonotonic changes with the distance to anthropogenic features, with a peak occurring at 4.5 km away from these features. This aggregation near disturbed areas thus provides the predators of this top-down-controlled, threatened herbivore species with specific locations to concentrate their search. The edge-effect theory developed here thus predicts that human activities should alter animal distribution and food web properties differently than anticipated from the current paradigm. Consideration of such nonmonotonic response to habitat edges may become essential to successful wildlife conservation.
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Affiliation(s)
- Daniel Fortin
- Chaire de Recherche Industrielle, Conseil de recherches en sciences naturelles et en génie du Canada (CRSNG)-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, Québec G1V 0A6 Canada.
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Edges in agricultural landscapes: species interactions and movement of natural enemies. PLoS One 2013; 8:e59659. [PMID: 23555737 PMCID: PMC3608671 DOI: 10.1371/journal.pone.0059659] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 02/16/2013] [Indexed: 11/29/2022] Open
Abstract
Agricultural landscapes can be characterized as a mosaic of habitat patches interspersed with hostile matrix, or as a gradient of patches ranging from suitable to unsuitable for different species. Arthropods moving through these landscapes encounter a range of edges, with different permeability. Patches of native vegetation in these landscapes may support natural enemies of crop pests by providing alternate hosts for parasitic wasps and/or acting as a source for predatory insects. We test this by quantifying species interactions and measuring movement across different edge-types. A high diversity of parasitoid species used hosts in the native vegetation patches, however we recorded few instances of the same parasitoid species using hosts in both the native vegetation and the crop (canola). However, we did find overall greater densities of parasitoids moving from native vegetation into the crop. Of the parasitoid groups examined, parasitoids of aphids (Braconidae: Aphidiinae) frequently moved from native vegetation into canola. In contrast, parasitoids of caterpillars (Braconidae: Microgastrinae) moved commonly from cereal fields into canola. Late season samples showed both aphids and parasitoids moving frequently out of native vegetation, in contrast predators moved less commonly from native vegetation (across the whole season). The season-long net advantage or disadvantage of native vegetation for pest control services is therefore difficult to evaluate. It appears that the different edge-types alter movement patterns of natural enemies more so than herbivorous pest species, and this may impact pest control services.
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Abstract
Because patch size and connectivity may strongly impact the assemblage of species that occur on a patch, the types of food-web interactions that occur among those species may also depend on spatial structure. Here, we identify whether food-web interactions among salt-marsh-inhabiting arthropods vary with patch size and connectivity, and how such changes in trophic structure might feed back to influence the spatial distribution of prey. In a multiyear survey, patch-restricted predators exhibited steeper occupancy-patch-size relationships than herbivores, and species' critical patch sizes were correlated with overall rarity. As a result, the presence of food-web modules depended strongly on patch size: large and well-connected patches supported complex food-web modules, but only the simplest modules involving the most abundant species were found on small patches. Habitat-generalist spiders dominated on small patches, and predation pressure from such species may contribute to the observed lower densities of mesopredators on small patches. Overall, patch size and connectivity influenced the types of modules present on a patch through differential loss of rare, patch-restricted predators, but predation by generalist predators may be a key mechanism influencing the spatial structure of certain prey species.
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Affiliation(s)
- Holly M Martinson
- Behavior, Ecology, Evolution, and Systematics Program, University of Maryland, College Park, Maryland 20742, USA.
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