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Feng T, Milne R, Wang H. Variation in environmental stochasticity dramatically affects viability and extinction time in a predator-prey system with high prey group cohesion. Math Biosci 2023; 365:109075. [PMID: 37734536 DOI: 10.1016/j.mbs.2023.109075] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 08/13/2023] [Accepted: 09/06/2023] [Indexed: 09/23/2023]
Abstract
Understanding how tipping points arise is critical for population protection and ecosystem robustness. This work evaluates the impact of environmental stochasticity on the emergence of tipping points in a predator-prey system subject to the Allee effect and Holling type IV functional response, modeling an environment in which the prey has high group cohesion. We analyze the relationship between stochasticity and the probability and time that predator and prey populations in our model tip between different steady states. We evaluate the safety from extinction of different population values for each species, and accordingly assign extinction warning levels to these population values. Our analysis suggests that the effects of environmental stochasticity on tipping phenomena are scenario-dependent but follow a few interpretable trends. The probability of tipping towards a steady state in which one or both species go extinct generally monotonically increased with noise intensity, while the probability of tipping towards a more favorable steady state (in which more species were viable) usually peaked at intermediate noise intensity. For tipping between two equilibria where a given species was at risk of extinction in one equilibrium but not the other, noise affecting that species had greater impact on tipping probability than noise affecting the other species. Noise in the predator population facilitated quicker tipping to extinction equilibria, whereas prey noise instead often slowed down extinction. Changes in warning level for initial population values due to noise were most apparent near attraction basin boundaries, but noise of sufficient magnitude (especially in the predator population) could alter risk even far away from these boundaries. Our model provides critical theoretical insights for the conservation of population diversity: management criteria and early warning signals can be developed based on our results to keep populations away from destructive critical thresholds.
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Affiliation(s)
- Tao Feng
- School of Mathematical Science, Yangzhou University, Yangzhou, Jiangsu 225002, PR China.
| | - Russell Milne
- Department of Mathematical and Statistical Sciences & Interdisciplinary Lab for Mathematical Ecology and Epidemiology, University of Alberta, Edmonton, AB T6G 2G1, Canada.
| | - Hao Wang
- Department of Mathematical and Statistical Sciences & Interdisciplinary Lab for Mathematical Ecology and Epidemiology, University of Alberta, Edmonton, AB T6G 2G1, Canada.
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2
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Beardsell A, Berteaux D, Dulude-De Broin F, Gauthier G, Clermont J, Gravel D, Bêty J. Predator-mediated interactions through changes in predator home range size can lead to local prey exclusion. Proc Biol Sci 2023; 290:20231154. [PMID: 37554032 PMCID: PMC10410220 DOI: 10.1098/rspb.2023.1154] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 07/12/2023] [Indexed: 08/10/2023] Open
Abstract
The strength of indirect biotic interactions is difficult to quantify in the wild and can alter community composition. To investigate whether the presence of a prey species affects the population growth rate of another prey species, we quantified predator-mediated interaction strength using a multi-prey mechanistic model of predation and a population matrix model. Models were parametrized using behavioural, demographic and experimental data from a vertebrate community that includes the arctic fox (Vulpes lagopus), a predator feeding on lemmings and eggs of various species such as sandpipers and geese. We show that the positive effects of the goose colony on sandpiper nesting success (due to reduction of search time for sandpiper nests) were outweighed by the negative effect of an increase in fox density. The fox numerical response was driven by changes in home range size. As a result, the net interaction from the presence of geese was negative and could lead to local exclusion of sandpipers. Our study provides a rare empirically based model that integrates mechanistic multi-species functional responses and behavioural processes underlying the predator numerical response. This is an important step forward in our ability to quantify the consequences of predation for community structure and dynamics.
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Affiliation(s)
- Andréanne Beardsell
- Chaire de recherche du Canada en biodiversité nordique, Centre d'études nordiques et Centre de la science de la biodiversité du Québec, Université du Québec à Rimouski, Rimouski, Québec, Canada G5L 3A1
| | - Dominique Berteaux
- Chaire de recherche du Canada en biodiversité nordique, Centre d'études nordiques et Centre de la science de la biodiversité du Québec, Université du Québec à Rimouski, Rimouski, Québec, Canada G5L 3A1
| | | | - Gilles Gauthier
- Département de biologie et Centre d'études nordiques, Université Laval, Québec, Canada G1V 0A6
| | - Jeanne Clermont
- Chaire de recherche du Canada en biodiversité nordique, Centre d'études nordiques et Centre de la science de la biodiversité du Québec, Université du Québec à Rimouski, Rimouski, Québec, Canada G5L 3A1
| | - Dominique Gravel
- Département de biologie et Centre d'études nordiques, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1
| | - Joël Bêty
- Chaire de recherche du Canada en biodiversité nordique, Centre d'études nordiques et Centre de la science de la biodiversité du Québec, Université du Québec à Rimouski, Rimouski, Québec, Canada G5L 3A1
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3
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McLellan ML, Dickie M, Boutin S, Becker M, Ernst B, Peel D, Zimmerman KL, Serrouya R. Prioritizing populations based on recovery potential. CONSERVATION SCIENCE AND PRACTICE 2023. [DOI: 10.1111/csp2.12905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Affiliation(s)
| | - Melanie Dickie
- Wildlife Science Centre Biodiversity Pathways Mill Bay British Columbia Canada
| | - Stan Boutin
- Department of Biological Sciences University of Alberta Edmonton Alberta Canada
| | - Marcus Becker
- Caribou Monitoring Unit, Alberta Biodiversity Monitoring Institute University of Alberta Edmonton Alberta Canada
| | - Bevan Ernst
- Caribou Monitoring Unit, Alberta Biodiversity Monitoring Institute University of Alberta Edmonton Alberta Canada
- Ministry of Land Water and Resource Stewardship Kamloops British Columbia Canada
| | - Darcy Peel
- Caribou Monitoring Unit, Alberta Biodiversity Monitoring Institute University of Alberta Edmonton Alberta Canada
- Ministry of Land Water and Resource Stewardship Kamloops British Columbia Canada
| | - Kathryn L. Zimmerman
- Caribou Monitoring Unit, Alberta Biodiversity Monitoring Institute University of Alberta Edmonton Alberta Canada
- Ministry of Land Water and Resource Stewardship Kamloops British Columbia Canada
| | - Robert Serrouya
- Wildlife Science Centre Biodiversity Pathways Mill Bay British Columbia Canada
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4
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Brandell EE, Cross PC, Smith DW, Rogers W, Galloway N, MacNulty DR, Stahler DR, Treanor J, Hudson PJ. Examination of the interaction between age-specific predation and chronic disease in the Greater Yellowstone Ecosystem. J Anim Ecol 2022; 91:1373-1384. [PMID: 34994978 PMCID: PMC9912199 DOI: 10.1111/1365-2656.13661] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 12/28/2021] [Indexed: 11/27/2022]
Abstract
Predators may create healthier prey populations by selectively removing diseased individuals. Predators typically prefer some ages of prey over others, which may, or may not, align with those prey ages that are most likely to be diseased. The interaction of age-specific infection and predation has not been previously explored and likely has sizable effects on disease dynamics. We hypothesize that predator cleansing effects will be greater when the disease and predation occur in the same prey age groups. We examine the predator cleansing effect using a model where both vulnerability to predators and pathogen prevalence vary with age. We tailor this model to chronic wasting disease (CWD) in mule deer and elk populations in the Greater Yellowstone Ecosystem, with empirical data from Yellowstone grey wolves and cougars. Model results suggest that under moderate, yet realistic, predation pressure from cougars and wolves independently, predators may decrease CWD outbreak size substantially and delay the accumulation of symptomatic deer and elk. The magnitude of this effect is driven by the ability of predators to selectively remove late-stage CWD infections that are likely the most responsible for transmission, but this may not be the age class they typically select. Thus, predators that select for infected young adults over uninfected juveniles have a stronger cleansing effect, and these effects are strengthened when transmission rates increase with increasing prey morbidity. There are also trade-offs from a management perspective-that is, increasing predator kill rates can result in opposing forces on prey abundance and CWD prevalence. Our modelling exploration shows that predators have the potential to reduce prevalence in prey populations when prey age and disease severity are considered, yet the strength of this effect is influenced by predators' selection for demography or body condition. Current CWD management focuses on increasing cervid hunting as the primary management tool, and our results suggest predators may also be a useful tool under certain conditions, but not necessarily without additional impacts on host abundance and demography. Protected areas with predator populations will play a large role in informing the debate over predator impacts on disease.
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Affiliation(s)
- Ellen E. Brandell
- Center for Infectious Disease Dynamics and Department of Biology, Huck Institutes of the Life SciencesPennsylvania State UniversityUniversity ParkPAUSA,Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife EcologyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Paul C. Cross
- U.S. Geological SurveyNorthern Rocky Mountain Science CenterBozemanMTUSA
| | - Douglas W. Smith
- Yellowstone Center for ResourcesYellowstone National ParkWyomingWYUSA
| | - Will Rogers
- Department of EcologyMontana State UniversityBozemanMTUSA
| | | | | | - Daniel R. Stahler
- Yellowstone Center for ResourcesYellowstone National ParkWyomingWYUSA
| | - John Treanor
- Yellowstone Center for ResourcesYellowstone National ParkWyomingWYUSA
| | - Peter J. Hudson
- Center for Infectious Disease Dynamics and Department of Biology, Huck Institutes of the Life SciencesPennsylvania State UniversityUniversity ParkPAUSA
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5
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Gobin J, Hossie TJ, Derbyshire RE, Sonnega S, Cambridge TW, Scholl L, Kloch ND, Scully A, Thalen K, Smith G, Scott C, Quinby F, Reynolds J, Miller HA, Faithfull H, Lucas O, Dennison C, McDonald J, Boutin S, O’Donoghue M, Krebs CJ, Boonstra R, Murray DL. Functional Responses Shape Node and Network Level Properties of a Simplified Boreal Food Web. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.898805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Ecological communities are fundamentally connected through a network of trophic interactions that are often complex and difficult to model. Substantial variation exists in the nature and magnitude of these interactions across various predators and prey and through time. However, the empirical data needed to characterize these relationships are difficult to obtain in natural systems, even for relatively simple food webs. Consequently, prey-dependent relationships and specifically the hyperbolic form (Holling’s Type II), in which prey consumption increases with prey density but ultimately becomes saturated or limited by the time spent handling prey, are most widely used albeit often without knowledge of their appropriateness. Here, we investigate the sensitivity of a simplified food web model for a natural, boreal system in the Kluane region of the Yukon, Canada to the type of functional response used. Intensive study of this community has permitted best-fit functional response relationships to be determined, which comprise linear (type I), hyperbolic (type II), sigmoidal (type III), prey- and ratio-dependent relationships, and inverse relationships where kill rates of alternate prey are driven by densities of the focal prey. We compare node- and network-level properties for a food web where interaction strengths are estimated using best-fit functional responses to one where interaction strengths are estimated exclusively using prey-dependent hyperbolic functional responses. We show that hyperbolic functional responses alone fail to capture important ecological interactions such as prey switching, surplus killing and caching, and predator interference, that in turn affect estimates of cumulative kill rates, vulnerability of prey, generality of predators, and connectance. Exclusive use of hyperbolic functional responses also affected trends observed in these metrics over time and underestimated annual variation in several metrics, which is important given that interaction strengths are typically estimated over relatively short time periods. Our findings highlight the need for more comprehensive research aimed at characterizing functional response relationships when modeling predator-prey interactions and food web structure and function, as we work toward a mechanistic understanding linking food web structure and community dynamics in natural systems.
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6
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Beardsell A, Gravel D, Clermont J, Berteaux D, Gauthier G, Bêty J. A mechanistic model of functional response provides new insights into indirect interactions among arctic tundra prey. Ecology 2022; 103:e3734. [DOI: 10.1002/ecy.3734] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 03/07/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Andréanne Beardsell
- Chaire de recherche du Canada en biodiversité nordique, Centre d’études nordiques et Centre de la science de la biodiversité du Québec Université du Québec à Rimouski Rimouski Québec Canada
| | - Dominique Gravel
- Département de biologie et Centre d’études nordiques Université de Sherbrooke Sherbrooke Québec Canada
| | - Jeanne Clermont
- Chaire de recherche du Canada en biodiversité nordique, Centre d’études nordiques et Centre de la science de la biodiversité du Québec Université du Québec à Rimouski Rimouski Québec Canada
| | - Dominique Berteaux
- Chaire de recherche du Canada en biodiversité nordique, Centre d’études nordiques et Centre de la science de la biodiversité du Québec Université du Québec à Rimouski Rimouski Québec Canada
| | - Gilles Gauthier
- Département de biologie et Centre d’études nordiques Université Laval Québec Québec Canada
| | - Joël Bêty
- Chaire de recherche du Canada en biodiversité nordique, Centre d’études nordiques et Centre de la science de la biodiversité du Québec Université du Québec à Rimouski Rimouski Québec Canada
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7
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Lochhead KD, Kleynhans EJ, Muhly TB. Linking woodland caribou abundance to forestry disturbance in southern British Columbia, Canada. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Kyle D. Lochhead
- Ministry of Forest Lands, Natural Resource Operations and Rural Development PO Box 9512, Stn. Prov. Govt. Victoria, BC V8W 9C2 Canada
| | - Elizabeth J. Kleynhans
- Ministry of Forest Lands, Natural Resource Operations and Rural Development PO Box 9512, Stn. Prov. Govt. Victoria, BC V8W 9C2 Canada
| | - Tyler B. Muhly
- Ministry of Forest Lands, Natural Resource Operations and Rural Development PO Box 9512, Stn. Prov. Govt. Victoria, BC V8W 9C2 Canada
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8
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Phumanee W, Steinmetz R, Phoonjampa R, Bejraburnin T, Grainger M, Savini T. Occupancy‐based monitoring of ungulate prey species in Thailand indicates population stability, but limited recovery. Ecosphere 2020. [DOI: 10.1002/ecs2.3208] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Worrapan Phumanee
- Conservation Ecology Program School of Bioresources and Technology King Mongkut's University of Technology Thonburi Bangkhuntien Bangkok10150Thailand
- WWF‐Thailand 9 Pisit Building, Pradiphat Road Soi 10 Phayathai Bangkok10400Thailand
| | - Robert Steinmetz
- WWF‐Thailand 9 Pisit Building, Pradiphat Road Soi 10 Phayathai Bangkok10400Thailand
| | - Rungnapa Phoonjampa
- WWF‐Thailand 9 Pisit Building, Pradiphat Road Soi 10 Phayathai Bangkok10400Thailand
| | - Thawatchai Bejraburnin
- Department of National Parks, Wildlife and Plant Conservation 61 Phaholyothin Road Bangkok10900Thailand
| | | | - Tommaso Savini
- Conservation Ecology Program School of Bioresources and Technology King Mongkut's University of Technology Thonburi Bangkhuntien Bangkok10150Thailand
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9
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Merrill E, Killeen J, Pettit J, Trottier M, Martin H, Berg J, Bohm H, Eggeman S, Hebblewhite M. Density-Dependent Foraging Behaviors on Sympatric Winter Ranges in a Partially Migratory Elk Population. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00269] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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10
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Fryxell JM, Avgar T, Liu B, Baker JA, Rodgers AR, Shuter J, Thompson ID, Reid DEB, Kittle AM, Mosser A, Newmaster SG, Nudds TD, Street GM, Brown GS, Patterson B. Anthropogenic Disturbance and Population Viability of Woodland Caribou in Ontario. J Wildl Manage 2020. [DOI: 10.1002/jwmg.21829] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- John M. Fryxell
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Tal Avgar
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Boyan Liu
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - James A. Baker
- Ontario Ministry of Natural Resources and ForestryWildlife Research and Monitoring Section 300 Water Street, Peterborough Ontario K9J 8M5 Canada
| | - Arthur R. Rodgers
- Ontario Ministry of Natural Resources and ForestryCentre for Northern Forest Ecosystem Research 435 James Street Thunder‐Bay Ontario P7E 2VE Canada
| | - Jennifer Shuter
- Ontario Ministry of Natural Resources and ForestryCentre for Northern Forest Ecosystem Research 435 James Street Thunder‐Bay Ontario P7E 2VE Canada
| | - Ian D. Thompson
- Canadian Forest Service 1219 Queen Street East, Sault Ste. Marie Ontario P6A 2E5 Canada
| | - Douglas E. B. Reid
- Ontario Ministry of Natural Resources and ForestryCentre for Northern Forest Ecosystem Research 435 James Street Thunder‐Bay Ontario P7E 2VE Canada
| | - Andrew M. Kittle
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Anna Mosser
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Steven G. Newmaster
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Tom D. Nudds
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Garrett M. Street
- Department of Integrative BiologyUniversity of Guelph 50 Stone Road E., Guelph Ontario N1G 2W1 Canada
| | - Glen S. Brown
- Ontario Ministry of Natural Resources and ForestryWildlife Research and Monitoring Section 300 Water Street, Peterborough Ontario K9J 8M5 Canada
| | - Brent Patterson
- Ontario Ministry of Natural Resources and ForestryWildlife Research and Monitoring Section 300 Water Street, Peterborough Ontario K9J 8M5 Canada
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11
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12
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Adams LG, Farnell R, Oakley MP, Jung TS, Larocque LL, Lortie GM, Mclelland J, Reid ME, Roffler GH, Russell DE. Evaluation of Maternal Penning to Improve Calf Survival in the Chisana Caribou Herd. WILDLIFE MONOGRAPHS 2019. [DOI: 10.1002/wmon.1044] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Layne G. Adams
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage AK 99508 USA
| | - Richard Farnell
- Yukon Department of Environment Fish and Wildlife Branch P. O. Box 2703 Whitehorse YT Y1A 2C6 Canada
| | - Michelle P. Oakley
- Yukon Department of Environment Fish and Wildlife Branch P. O. Box 5429 Haines Junction YT Y0B 1L0 Canada
| | - Thomas S. Jung
- Yukon Department of Environment Fish and Wildlife Branch P. O. Box 2703 Whitehorse YT Y1A 2C6 Canada
| | - Lorne L. Larocque
- Yukon Department of Environment Fish and Wildlife Branch P. O. Box 5429 Haines Junction YT Y0B 1L0 Canada
| | | | - Jamie Mclelland
- Yukon Department of Environment Fish and Wildlife Branch P. O. Box 2703 Whitehorse YT Y1A 2C6 Canada
| | - Mason E. Reid
- U.S. National Park Service Wrangell‐St. Elias National Park and Preserve, P. O. Box 439, Copper Center, AK 99573 USA
| | - Gretchen H. Roffler
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage AK 99508 USA
| | - Don E. Russell
- Canadian Wildlife Service 91782 Alaska Highway Whitehorse YT Y1A 5B7 Canada
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13
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Cristescu B, Bose S, Elbroch LM, Allen ML, Wittmer HU. Habitat selection when killing primary versus alternative prey species supports prey specialization in an apex predator. J Zool (1987) 2019. [DOI: 10.1111/jzo.12718] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- B. Cristescu
- Environmental Studies Department University of California Santa Cruz CA USA
| | - S. Bose
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand
| | | | - M. L. Allen
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand
- Illinois Natural History Survey University of Illinois Champaign IL USA
| | - H. U. Wittmer
- School of Biological Sciences Victoria University of Wellington Wellington New Zealand
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14
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Westwood AR, Otto SP, Mooers A, Darimont C, Hodges KE, Johnson C, Starzomski BM, Burton C, Chan KM, Festa-Bianchet M, Fluker S, Gulati S, Jacob AL, Kraus D, Martin TG, Palen WJ, Reynolds JD, Whitton J. Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation. Facets (Ott) 2019. [DOI: 10.1139/facets-2018-0042] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act.
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Affiliation(s)
- Alana R. Westwood
- Yellowstone to Yukon Conservation Initiative, 200-1350 Railway Avenue, Canmore, AB T1W 1P6, Canada
| | - Sarah P. Otto
- Biodiversity Research Centre & Department of Zoology, The University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
| | - Arne Mooers
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Chris Darimont
- Department of Geography, University of Victoria, P.O. Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Karen E. Hodges
- Department of Biology, The University of British Columbia—Okanagan Campus, 1177 Research Road, Kelowna, BC V1V 1V7, Canada
| | - Chris Johnson
- Ecosystem Science & Management Program, University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9, Canada
| | - Brian M. Starzomski
- School of Environmental Studies, University of Victoria, P.O. Box 3060 STN CSC, Victoria, BC V8W 3R4, Canada
| | - Cole Burton
- Department of Forest Resources Management, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Kai M.A. Chan
- Institute for Resources, Environment and Sustainability, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Marco Festa-Bianchet
- Département de biologie, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada
| | - Shaun Fluker
- Faculty of Law, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada
| | - Sumeet Gulati
- Faculty of Land and Food Systems, The University of British Columbia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Aerin L. Jacob
- Yellowstone to Yukon Conservation Initiative, 200-1350 Railway Avenue, Canmore, AB T1W 1P6, Canada
| | - Dan Kraus
- School of Environment, Resources and Sustainability, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Tara G. Martin
- Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Wendy J. Palen
- Earth to Ocean Research Group, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - John D. Reynolds
- Earth to Ocean Research Group, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeannette Whitton
- Biodiversity Research Centre & Department of Botany, The University of British Columbia, 6270 University Boulevard, Vancouver, BC V6T 1Z4, Canada
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15
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Ng'weno CC, Buskirk SW, Georgiadis NJ, Gituku BC, Kibungei AK, Porensky LM, Rubenstein DI, Goheen JR. Apparent Competition, Lion Predation, and Managed Livestock Grazing: Can Conservation Value Be Enhanced? Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00123] [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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16
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Boivin T, Doublet V, Candau JN. The ecology of predispersal insect herbivory on tree reproductive structures in natural forest ecosystems. INSECT SCIENCE 2019; 26:182-198. [PMID: 29082661 DOI: 10.1111/1744-7917.12549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/06/2017] [Accepted: 08/15/2017] [Indexed: 06/07/2023]
Abstract
Plant-insect interactions are key model systems to assess how some species affect the distribution, the abundance, and the evolution of others. Tree reproductive structures represent a critical resource for many insect species, which can be likely drivers of demography, spatial distribution, and trait diversification of plants. In this review, we present the ecological implications of predispersal herbivory on tree reproductive structures by insects (PIHR) in forest ecosystems. Both insect's and tree's perspectives are addressed with an emphasis on how spatiotemporal variation and unpredictability in seed availability can shape such particular plant-animal interactions. Reproductive structure insects show strong trophic specialization and guild diversification. Insects evolved host selection and spatiotemporal dispersal strategies in response to variable and unpredictable abundance of reproductive structures in both space and time. If PIHR patterns have been well documented in numerous systems, evidences of the subsequent demographic and evolutionary impacts on tree populations are still constrained by time-scale challenges of experimenting on such long-lived organisms, and modeling approaches of tree dynamics rarely consider PIHR when including biotic interactions in their processes. We suggest that spatially explicit and mechanistic approaches of the interactions between individual tree fecundity and insect dynamics will clarify predictions of the demogenetic implications of PIHR in tree populations. In a global change context, further experimental and theoretical contributions to the likelihood of life-cycle disruptions between plants and their specialized herbivores, and to how these changes may generate novel dynamic patterns in each partner of the interaction are increasingly critical.
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Affiliation(s)
| | | | - Jean-Noël Candau
- Natural Resources Canada, Canadian Forest Service, Great Lakes Forestry Centre, Sault Ste Marie, Ontario, Canada
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17
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Martin H, Mech L, Fieberg J, Metz M, MacNulty D, Stahler D, Smith D. Factors affecting gray wolf (Canis lupus) encounter rate with elk (Cervus elaphus) in Yellowstone National Park. CAN J ZOOL 2018. [DOI: 10.1139/cjz-2017-0220] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite encounter rates being a key component of kill rate, few studies of large carnivore predation have quantified encounter rates with prey, the factors that influence them, and the relationship between encounter rate and kill rate. The study’s primary motivation was to determine the relationship between prey density and encounter rate in understanding the mechanism behind the functional response. Elk (Cervus elaphus Linnaeus, 1758) population decline and variable weather in northern Yellowstone National Park provided an opportunity to examine how these factors influenced wolf (Canis lupus Linnaeus, 1758) encounter rates with elk. We explored how factors associated with wolf kill rate and encounter rate in other systems (season, elk density, elk group density, average elk group size, snow depth, wolf pack size, and territory size) influenced wolf–elk encounter rate in Yellowstone National Park. Elk density was the only factor significantly correlated with wolf–elk encounter rate, and we found a nonlinear density-dependent relationship that may be a mechanism for a functional response in this system. Encounter rate was correlated with number of elk killed during early winter but not late winter. Weak effects of snow depth and elk group size on encounter rate suggest that these factors influence kill rate via hunting success because kill rate is the product of hunting success and encounter rate.
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Affiliation(s)
- H.W. Martin
- Fisheries, Wildlife/Conservation Biology, University of Minnesota-Twin Cities, Room 135, Skok Hall, 2003 Upper Buford Circle, St. Paul, MN 55108, USA
| | - L.D. Mech
- US Geological Survey, Northern Prairie Wildlife Research Center, 8711-37th Street SE, Jamestown, ND 58401, USA
| | - J. Fieberg
- Fisheries, Wildlife/Conservation Biology, University of Minnesota-Twin Cities, Room 135, Skok Hall, 2003 Upper Buford Circle, St. Paul, MN 55108, USA
| | - M.C. Metz
- W.A. Franke College of Forestry and Conservation, University of Montana-Missoula, 32 Campus Drive, Missoula, MT 59812, USA
| | - D.R. MacNulty
- Department of Wildland Resources, Utah State University, 5230 Old Main Hill, Logan, UT 84322, USA
| | - D.R. Stahler
- Yellowstone Center for Resources, P.O. Box 168, Yellowstone National Park, WY 82190, USA
| | - D.W. Smith
- Yellowstone Center for Resources, P.O. Box 168, Yellowstone National Park, WY 82190, USA
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18
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Elliott KH, Betini GS, Norris DR. Fear creates an Allee effect: experimental evidence from seasonal populations. Proc Biol Sci 2017; 284:rspb.2017.0878. [PMID: 28659452 DOI: 10.1098/rspb.2017.0878] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/26/2017] [Indexed: 11/12/2022] Open
Abstract
Allee effects driven by predation can play a strong role in the decline of small populations but are conventionally thought to occur when generalist predators target specific prey (i.e. type II functional response). However, aside from direct consumption, fear of predators could also increase vigilance and reduce time spent foraging as population size decreases, as has been observed in wild mammals living in social groups. To investigate the role of fear on fitness in relation to population density in a species with limited sociality, we exposed varying densities of Drosophila melanogaster to mantid predators either during an experimental breeding season or non-breeding season. The presence of mantids in either season decreased the reproductive performance of individuals but only at low breeding densities, providing evidence for an Allee effect. We then used our experimental results to parametrize a mathematical model to examine the population consequences of fear at low densities. Fear tended to destabilize population dynamics and increase the risk of extinction up to sevenfold. Our study provides unique experimental evidence that the indirect effects of the presence of predators can cause an Allee effect and has important consequences for our understanding of the dynamics of small populations.
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Affiliation(s)
- Kyle H Elliott
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 .,Department of Natural Resource Sciences, McGill University, Ste Anne-de-Bellevue, Quebec, Canada H9X 3V9
| | - Gustavo S Betini
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - D Ryan Norris
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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19
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20
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Leech H, Jelinski D, DeGroot L, Kuzyk G. The temporal niche and seasonal differences in predation risk to translocated and resident woodland caribou (Rangifer tarandus caribou). CAN J ZOOL 2017. [DOI: 10.1139/cjz-2016-0076] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mountain caribou are an endangered ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) that continue to decline, ultimately, due to habitat loss and, proximately, due to predation. A particularly imperilled population of mountain caribou was experimentally augmented with 19 northern caribou, a geographically distinct ecotype, from northern British Columbia. We examined seasonal variation in risk of predation by cougars (Puma concolor (L., 1771)) to the translocated caribou with comparison to resident caribou. Our basic approach followed the Movement Ecology Paradigm, in particular the interplay among why move, and when and where to move. We applied a cluster analysis framework on space-use patterns of GPS radio-collared animals to determine biologically relevant seasons. Then we examined the spatiotemporal similarity in habitat use between caribou groups and cougars across these seasons. This analysis included a control group of caribou from the donor herd that were not translocated. Five resident caribou seasons, two donor caribou seasons, and two cougar seasons were identified. Resident caribou remained at high elevations year-round and primarily selected habitats not used by cougars. In contrast, translocated caribou tended to occupy low-elevation habitats extensively used by cougars, resulting in predation of eight translocated caribou, six of which were by cougars. We concluded that the translocated caribou did not adopt the predator avoidance strategies of resident caribou, rendering them more vulnerable to predation. We make recommendations for future herd augmentations, notably that donor caribou should be of the same ecotype, have similar seasonal patterns of habitat use and associated behavioural repertoires, and be exposed to the same complex of predators.
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Affiliation(s)
- H. Leech
- Laboratory for Landscape and Wildlife Ecology, Department of Geography, University of Victoria, Victoria, BC V8W 3R4, Canada
| | - D.E. Jelinski
- Laboratory for Landscape and Wildlife Ecology, Department of Geography, University of Victoria, Victoria, BC V8W 3R4, Canada
| | - L. DeGroot
- Ministry of Forests, Lands and Natural Resource Operations, 333 Victoria Street, Nelson, BC V1L 4K3, Canada
| | - G. Kuzyk
- Ministry of Forests, Lands and Natural Resource Operations, Victoria, BC V8W 9M8, Canada
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21
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Wilman EA, Wilman EN. Fast, slow, and adaptive management of habitat modification-invasion interactions: woodland caribou (Rangifer tarandus
). Ecosphere 2017. [DOI: 10.1002/ecs2.1970] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Elizabeth A. Wilman
- Department of Economics; University of Calgary; Calgary Alberta T2N1N4 Canada
| | - Elspeth N. Wilman
- Department of Ecology & Biodiversity; School of Biological Sciences; The University of Hong Kong; Hong Kong SAR China
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22
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Serrouya R, McLellan BN, van Oort H, Mowat G, Boutin S. Experimental moose reduction lowers wolf density and stops decline of endangered caribou. PeerJ 2017; 5:e3736. [PMID: 28875080 PMCID: PMC5580390 DOI: 10.7717/peerj.3736] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/04/2017] [Indexed: 11/30/2022] Open
Abstract
The expansion of moose into southern British Columbia caused the decline and extirpation of woodland caribou due to their shared predators, a process commonly referred to as apparent competition. Using an adaptive management experiment, we tested the hypothesis that reducing moose to historic levels would reduce apparent competition and therefor recover caribou populations. Nested within this broad hypothesis were three specific hypotheses: (1) sport hunting could be used to substantially reduce moose numbers to an ecological target; (2) wolves in this ecosystem were primarily limited by moose abundance; and (3) caribou were limited by wolf predation. These hypotheses were evaluated with a before-after control-impact (BACI) design that included response metrics such as population trends and vital rates of caribou, moose, and wolves. Three caribou subpopulations were subject to the moose reduction treatment and two were in a reference area where moose were not reduced. When the moose harvest was increased, the moose population declined substantially in the treatment area (by 70%) but not the reference area, suggesting that the policy had the desired effect and was not caused by a broader climatic process. Wolf numbers subsequently declined in the treatment area, with wolf dispersal rates 2.5× greater, meaning that dispersal was the likely mechanism behind the wolf numerical response, though reduced recruitment and starvation was also documented in the treatment area. Caribou adult survival increased from 0.78 to 0.88 in the treatment area, but declined in the reference. Caribou recruitment was unaffected by the treatment. The largest caribou subpopulation stabilized in the treatment area, but declined in the reference area. The observed population stability is comparable to other studies that used intensive wolf control, but is insufficient to achieve recovery, suggesting that multiple limiting factors and corresponding management tools must be addressed simultaneously to achieve population growth.
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Affiliation(s)
- Robert Serrouya
- Columbia Mountains Caribou Research Project, Revelstoke, British Columbia, Canada.,Alberta Biodiversity Monitoring Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Bruce N McLellan
- Columbia Mountains Caribou Research Project, Revelstoke, British Columbia, Canada.,Research Branch, Ministry of Forests, Lands, and Natural Resource Operations, D'Arcy, British Columbia, Canada
| | - Harry van Oort
- Columbia Mountains Caribou Research Project, Revelstoke, British Columbia, Canada
| | - Garth Mowat
- Natural Resource Science Section, Ministry of Forests, Lands, and Natural Resource Operations, Nelson, British Columbia, Canada.,Department of Earth and Environmental Sciences, University of British Columbia Okanagan Campus, Kelowna, British Columbia, Canada
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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23
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The complex dynamics of a diffusive prey–predator model with an Allee effect in prey. ECOLOGICAL COMPLEXITY 2016. [DOI: 10.1016/j.ecocom.2016.07.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Wittmann MJ, Stuis H, Metzler D. Genetic Allee effects and their interaction with ecological Allee effects. J Anim Ecol 2016; 87:11-23. [PMID: 27730641 DOI: 10.1111/1365-2656.12598] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/06/2016] [Indexed: 11/28/2022]
Abstract
It is now widely accepted that genetic processes such as inbreeding depression and loss of genetic variation can increase the extinction risk of small populations. However, it is generally unclear whether extinction risk from genetic causes gradually increases with decreasing population size or whether there is a sharp transition around a specific threshold population size. In the ecological literature, such threshold phenomena are called 'strong Allee effects' and they can arise for example from mate limitation in small populations. In this study, we aim to (i) develop a meaningful notion of a 'strong genetic Allee effect', (ii) explore whether and under what conditions such an effect can arise from inbreeding depression due to recessive deleterious mutations, and (iii) quantify the interaction of potential genetic Allee effects with the well-known mate-finding Allee effect. We define a strong genetic Allee effect as a genetic process that causes a population's survival probability to be a sigmoid function of its initial size. The inflection point of this function defines the critical population size. To characterize survival-probability curves, we develop and analyse simple stochastic models for the ecology and genetics of small populations. Our results indicate that inbreeding depression can indeed cause a strong genetic Allee effect, but only if individuals carry sufficiently many deleterious mutations (lethal equivalents). Populations suffering from a genetic Allee effect often first grow, then decline as inbreeding depression sets in and then potentially recover as deleterious mutations are purged. Critical population sizes of ecological and genetic Allee effects appear to be often additive, but even superadditive interactions are possible. Many published estimates for the number of lethal equivalents in birds and mammals fall in the parameter range where strong genetic Allee effects are expected. Unfortunately, extinction risk due to genetic Allee effects can easily be underestimated as populations with genetic problems often grow initially, but then crash later. Also interactions between ecological and genetic Allee effects can be strong and should not be neglected when assessing the viability of endangered or introduced populations.
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Affiliation(s)
| | - Hanna Stuis
- Leiden University Medical Center, Leiden, The Netherlands
| | - Dirk Metzler
- Department of Biology, Ludwig-Maximilans-Universität München, Martinsried, Germany
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25
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Tyson R, Lutscher F. Seasonally Varying Predation Behavior and Climate Shifts Are Predicted to Affect Predator-Prey Cycles. Am Nat 2016; 188:539-553. [DOI: 10.1086/688665] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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26
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Fortin D, Buono PL, Schmitz OJ, Courbin N, Losier C, St-Laurent MH, Drapeau P, Heppell S, Dussault C, Brodeur V, Mainguy J. A spatial theory for characterizing predator-multiprey interactions in heterogeneous landscapes. Proc Biol Sci 2016. [PMID: 26224710 DOI: 10.1098/rspb.2015.0973] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Trophic interactions in multiprey systems can be largely determined by prey distributions. Yet, classic predator-prey models assume spatially homogeneous interactions between predators and prey. We developed a spatially informed theory that predicts how habitat heterogeneity alters the landscape-scale distribution of mortality risk of prey from predation, and hence the nature of predator interactions in multiprey systems. The theoretical model is a spatially explicit, multiprey functional response in which species-specific advection-diffusion models account for the response of individual prey to habitat edges. The model demonstrates that distinct responses of alternative prey species can alter the consequences of conspecific aggregation, from increasing safety to increasing predation risk. Observations of threatened boreal caribou, moose and grey wolf interacting over 378 181 km(2) of human-managed boreal forest support this principle. This empirically supported theory demonstrates how distinct responses of apparent competitors to landscape heterogeneity, including to human disturbances, can reverse density dependence in fitness correlates.
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Affiliation(s)
- Daniel Fortin
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Pietro-Luciano Buono
- GIREF, Chaire de Recherche Industrielle du CRSNG en Calcul Scientifique, Département de Mathématiques et de Statistique, Université Laval, Québec, G1V 0A6, Canada Faculty of Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario, Canada
| | - Oswald J Schmitz
- Yale School of Forestry and Environmental Studies, 370 Prospect Street, New Haven, CT 06511, USA
| | - Nicolas Courbin
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Chrystel Losier
- Chaire de Recherche Industrielle CRSNG-Université Laval en Sylviculture et Faune, Département de Biologie, Université Laval, Québec, G1V 0A6, Canada
| | - Martin-Hugues St-Laurent
- Département de Biologie, Chimie et Géographie, Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, Canada
| | - Pierre Drapeau
- Chaire de Recherche Industrielle CRSNG-Université du Québec en Abitibi-Témiscamingue et Université du Québec à Montréal en aménagement forestier durable, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Canada
| | - Sandra Heppell
- Direction de la gestion de la faune de la Côte-Nord, Ministère des Forêts, de la Faune et des Parcs (MFFP), Baie-Comeau, Canada
| | - Claude Dussault
- Direction de la gestion de la faune du Saguenay-Lac-St-Jean, MFFP, Jonquière, Canada
| | - Vincent Brodeur
- Direction de la gestion de la faune du Nord-du-Québec, MFFP, Chibougamau, Canada
| | - Julien Mainguy
- Direction de la faune terrestre et de l'avifaune, MFFP, Québec, Canada
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27
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Bergerud AT, Mclaren BE, Krysl L, Wade K, Wyett W. Losing the predator—prey space race leads to extirpation of woodland caribou from Pukaskwa National Park. ECOSCIENCE 2015. [DOI: 10.2980/21-(3-4)-3700] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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28
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Serrouya R, Wittmann MJ, McLellan BN, Wittmer HU, Boutin S. Using predator-prey theory to predict outcomes of broadscale experiments to reduce apparent competition. Am Nat 2015; 185:665-79. [PMID: 25905509 DOI: 10.1086/680510] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Apparent competition is an important process influencing many ecological communities. We used predator-prey theory to predict outcomes of ecosystem experiments aimed at mitigating apparent competition by reducing primary prey. Simulations predicted declines in secondary prey following reductions in primary prey because predators consumed more secondary prey until predator numbers responded to reduced prey densities. Losses were exacerbated by a higher carrying capacity of primary prey and a longer lag time of the predator's numerical response, but a gradual reduction in primary prey was less detrimental to the secondary prey. We compared predictions against two field experiments where endangered woodland caribou (Rangifer tarandus caribou) were victims of apparent competition. First, when deer (Odocoileus sp.) declined suddenly following a severe winter, cougar (Puma concolor) declined with a 1-2-year lag, yet in the interim more caribou were killed by cougars, and caribou populations declined by 40%. Second, when moose (Alces alces) were gradually reduced using a management experiment, wolf (Canis lupus) populations declined but did not shift consumption to caribou, and the largest caribou subpopulation stabilized. The observed contrasting outcomes of sudden versus gradual declines in primary prey supported theoretical predictions. Combining theory with field studies clarified how to manage communities to mitigate endangerment caused by apparent competition that affects many taxa.
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Affiliation(s)
- Robert Serrouya
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
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29
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Elbroch LM, Allen ML, Lowrey BH, Wittmer HU. The difference between killing and eating: ecological shortcomings of puma energetic models. Ecosphere 2014. [DOI: 10.1890/es13-00373.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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30
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Silliman BR, McCoy MW, Angelini C, Holt RD, Griffin JN, van de Koppel J. Consumer Fronts, Global Change, and Runaway Collapse in Ecosystems. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2013. [DOI: 10.1146/annurev-ecolsys-110512-135753] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Brian R. Silliman
- Division of Marine Science and Conservation, Nicholas School of the Environment, Duke University, Beaufort, North Carolina 28516;
| | - Michael W. McCoy
- Department of Biology, East Carolina University, Greenville, North Carolina 27858
| | - Christine Angelini
- Department of Biology, University of Florida, Gainesville, Florida 32611
| | - Robert D. Holt
- Department of Biology, University of Florida, Gainesville, Florida 32611
| | - John N. Griffin
- Department of BioSciences, Swansea University, Swansea, SA2 8PP, Wales, United Kingdom
| | - Johan van de Koppel
- Spatial Ecology Department, Royal Netherlands Institute for Sea Research, 4401 NT Yerseke, The Netherlands
- Community and Conservation Ecology Group, University of Groningen, 9700 AB Groningen, The Netherlands
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31
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McQuaid CF, Britton NF. Trophic structure, stability, and parasite persistence threshold in food webs. Bull Math Biol 2013; 75:2196-207. [PMID: 23943365 DOI: 10.1007/s11538-013-9887-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 07/25/2013] [Indexed: 11/25/2022]
Abstract
Food web structure of free-living species is an important determinant of parasite species richness. Downwardly asymmetric predator-prey interactions (where there are more prey than predator species) have been shown, both theoretically and empirically, to harbour more trophically transmitted parasite species than expected due to chance. Here, we demonstrate that this could be due to the increase in the basic reproductive ratio that the addition of non-host prey species to a system creates. However, we note that the basic reproductive ratio is only increased by those prey that stabilise oscillations in a predator-prey system, and is decreased by those that do not.
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Affiliation(s)
- C Finn McQuaid
- Department of Mathematical Sciences, University of Bath, Bath, BA2 7AY, UK,
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32
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Xia J, Sun S, Liu G. Evidence of a component Allee effect driven by predispersal seed predation in a plant (Pedicularis rex, Orobanchaceae). Biol Lett 2013; 9:20130387. [PMID: 23925832 DOI: 10.1098/rsbl.2013.0387] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A small or sparse population may suffer a reduction in fitness owing to Allee effects. Here, we explored effects of plant density on pollination, reproduction and predation in the alpine herb Pedicularis rex over two years. We did not detect a significant difference in the pollination rate or fecundity (fruit set and the initial seed set) before predation between sparse and dense patches in either year, indicating no pollination-driven Allee effect. However, dense patches experienced significantly fewer attacks by predispersal seed predators in both years, resulting in a significantly decreased realized fecundity (final seed set), suggesting a component Allee effect driven by predispersal seed predation. Predation-driven Allee effects have been predicted by many models and demonstrated for a range of animals, but there is scant evidence for such effects in plants. Our study provides strong evidence of a component Allee effect driven by predation in a plant species.
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Affiliation(s)
- Jing Xia
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, The Chinese Academy of Sciences, Wuhan 430074, People's Republic of China.
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33
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Apps CD, Mclellan BN, Kinley TA, Serrouya R, Seip DR, Wittmer HU. Spatial factors related to mortality and population decline of endangered mountain caribou. J Wildl Manage 2013. [DOI: 10.1002/jwmg.601] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Clayton D. Apps
- Aspen Wildlife Research; 2708 Cochrane Road N.W. Calgary Alberta T2M 4H9 Canada
| | - Bruce N. Mclellan
- Ministry of Forests; Lands and Natural Resource Operations; RPO #3, Box 9158 Revelstoke British Columbia Canada
| | - Trevor A. Kinley
- Sylvan Consulting; RR5, 3519 Toby Creek Road Invermere British Columbia V0A 1K5 Canada
| | - Robert Serrouya
- Columbia Mountains Caribou Project; RPO #3, P.O. Box 9158 Revelstoke British Columbia V0E 3K0 Canada
| | - Dale R. Seip
- Ministry of Environment; 5th Floor, 1011-4th Ave. Prince George British Columbia V2L3H9 Canada
| | - Heiko U. Wittmer
- School of Biological Sciences; Victoria University of Wellington; P.O. Box 600 Wellington 6140 New Zealand
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34
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Wittmer HU, Serrouya R, Elbroch LM, Marshall AJ. Conservation strategies for species affected by apparent competition. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2013; 27:254-260. [PMID: 23282104 DOI: 10.1111/cobi.12005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/23/2012] [Indexed: 06/01/2023]
Abstract
Apparent competition is an indirect interaction between 2 or more prey species through a shared predator, and it is increasingly recognized as a mechanism of the decline and extinction of many species. Through case studies, we evaluated the effectiveness of 4 management strategies for species affected by apparent competition: predator control, reduction in the abundances of alternate prey, simultaneous control of predators and alternate prey, and no active management of predators or alternate prey. Solely reducing predator abundances rapidly increased abundances of alternate and rare prey, but observed increases are likely short-lived due to fast increases in predator abundance following the cessation of control efforts. Substantial reductions of an abundant alternate prey resulted in increased predation on endangered huemul (Hippocamelus bisulcus) deer in Chilean Patagonia, which highlights potential risks associated with solely reducing alternate prey species. Simultaneous removal of predators and alternate prey increased survival of island foxes (Urocyon littoralis) in California (U.S.A.) above a threshold required for population recovery. In the absence of active management, populations of rare woodland caribou (Rangifer tarandus caribou) continued to decline in British Columbia, Canada. On the basis of the cases we examined, we suggest the simultaneous control of predators and alternate prey is the management strategy most likely to increase abundances and probabilities of persistence of rare prey over the long term. Knowing the mechanisms driving changes in species' abundances before implementing any management intervention is critical. We suggest scientists can best contribute to the conservation of species affected by apparent competition by clearly communicating the biological and demographic forces at play to policy makers responsible for the implementation of proposed management actions.
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Affiliation(s)
- Heiko U Wittmer
- School of Biological Science, Victoria University of Wellington, Wellington, New Zealand.
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35
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Angulo E, Rasmussen GSA, Macdonald DW, Courchamp F. Do social groups prevent Allee effect related extinctions?: The case of wild dogs. Front Zool 2013; 10:11. [PMID: 23496951 PMCID: PMC3626796 DOI: 10.1186/1742-9994-10-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 03/02/2013] [Indexed: 11/10/2022] Open
Abstract
Background Allee effects may arise as the number of individuals decreases, thereby reducing opportunities for cooperation and constraining individual fitness, which can lead to population decrease and extinction. Obligate cooperative breeders rely on a minimum group size to subsist and are thus expected to be particularly susceptible to Allee effects. Although Allee effects in some components of the fitness of cooperative breeders have been detected, empirical confirmation of population extinction due to Allee effects is lacking yet. Because previous studies of cooperation have focused on Allee effects affecting individual fitness (component Allee effect) and population dynamics (demographic Allee effect), we argue that a new conceptual level of Allee effect, the group Allee effect, is needed to understand the special case of cooperative breeders. Results We hypothesize that whilst individuals are vulnerable to Allee effects, the group could act as a buffer against population extinction if: (i) individual fitness and group fate depend on group size but not on population size and (ii) group size is independent of population size (that is, at any population size, populations comprise both large and small groups). We found that both conditions apply for the African wild dog, Lycaon pictus, and data on this species in Zimbabwe support our hypothesis. Conclusions The importance of groups in obligate cooperative breeders needs to be accounted for within the Allee effect framework, through a group Allee effect, because the group mediates the relationship between individual fitness and population performance. Whilst sociality is associated with a high probability of Allee effects, we suggest that cooperative individuals organized in relatively autonomous groups within populations might be behaving in ways that diminish extinction risks caused by Allee effects. This study opens new avenues to a better understanding of the role of the evolution of group-living on the probability of extinction faced by social species.
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Affiliation(s)
- Elena Angulo
- Ecologie, Systématique & Evolution, UMR CNRS 8079, University Paris Sud, Orsay Cedex, 91405, France.,Estación Biológica de Doñana, CSIC, Avda. Americo Vespucio s/n, Sevilla, 41092, Spain
| | - Greg S A Rasmussen
- Wildlife Conservation Research Unit, Zoology Department, University of Oxford, The Recanati-Kaplan Centre, Tubney House, Tubney, Oxfordshire, OX13 5QL, UK
| | - David W Macdonald
- Wildlife Conservation Research Unit, Zoology Department, University of Oxford, The Recanati-Kaplan Centre, Tubney House, Tubney, Oxfordshire, OX13 5QL, UK
| | - Franck Courchamp
- Ecologie, Systématique & Evolution, UMR CNRS 8079, University Paris Sud, Orsay Cedex, 91405, France
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Forrester TD, Wittmer HU. A review of the population dynamics of mule deer and black-tailed deer Odocoileus hemionus
in North America. Mamm Rev 2013. [DOI: 10.1111/mam.12002] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Tavis D. Forrester
- Department of Wildlife, Fish, and Conservation Biology; University of California; One Shields Avenue Davis California 95616 USA
| | - Heiko U. Wittmer
- Department of Wildlife, Fish, and Conservation Biology; University of California; One Shields Avenue Davis California 95616 USA
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Elbroch LM, Wittmer HU. Nuisance ecology: do scavenging condors exact foraging costs on pumas in Patagonia? PLoS One 2013; 8:e53595. [PMID: 23301093 PMCID: PMC3536754 DOI: 10.1371/journal.pone.0053595] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 12/03/2012] [Indexed: 11/19/2022] Open
Abstract
Predation risk describes the energetic cost an animal suffers when making a trade off between maximizing energy intake and minimizing threats to its survival. We tested whether Andean condors (Vultur gryphus) influenced the foraging behaviors of a top predator in Patagonia, the puma (Puma concolor), in ways comparable to direct risks of predation for prey to address three questions: 1) Do condors exact a foraging cost on pumas?; 2) If so, do pumas exhibit behaviors indicative of these risks?; and 3) Do pumas display predictable behaviors associated with prey species foraging in risky environments? Using GPS location data, we located 433 kill sites of 9 pumas and quantified their kill rates. Based upon time pumas spent at a carcass, we quantified handling time. Pumas abandoned >10% of edible meat at 133 of 266 large carcasses after a single night, and did so most often in open grasslands where their carcasses were easily detected by condors. Our data suggested that condors exacted foraging costs on pumas by significantly decreasing puma handling times at carcasses, and that pumas increased their kill rates by 50% relative to those reported for North America to compensate for these losses. Finally, we determined that the relative risks of detection and associated harassment by condors, rather than prey densities, explained puma "giving up times" (GUTs) across structurally variable risk classes in the study area, and that, like many prey species, pumas disproportionately hunted in high-risk, high-resource reward areas.
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Affiliation(s)
- L Mark Elbroch
- Wildlife, Fish, and Conservation Biology, University of California Davis, Davis, California, United States of America.
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Johnson HE, Hebblewhite M, Stephenson TR, German DW, Pierce BM, Bleich VC. Evaluating apparent competition in limiting the recovery of an endangered ungulate. Oecologia 2012; 171:295-307. [DOI: 10.1007/s00442-012-2397-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/08/2012] [Indexed: 11/29/2022]
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McPhee HM, Webb NF, Merrill EH. Hierarchical predation: wolf (Canis lupus) selection along hunt paths and at kill sites. CAN J ZOOL 2012. [DOI: 10.1139/z2012-021] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Predation is a hierarchical process whereby a predator is constrained to killing prey within the area they select while hunting. We demonstrate the hierarchical nature of predation using movement data from six GPS-collared wolves ( Canis lupus L., 1758) in the Rocky Mountains of Alberta, Canada, by coupling the kill locations of their ungulate prey with their preceding hunt path. Selection of where to hunt constrained the characteristics influencing where wolves killed within hunt paths. Specifically, wolves selected to hunt where prey densities were higher than the mean density for their territories, but prey densities were not related to kill site locations within the selected hunt path. Wolves selected to hunt in open valleys and near habitat edges, where prey may be most predictable, detectable, or vulnerable, which may have been reinforced by a higher likelihood of killing within these characteristics along hunt paths. In contrast, wolves selected to hunt relatively farther from frozen water bodies and closer to well sites than kill site locations, indicating different processes were occurring during the hunting and killing phases. Treating predation as a hierarchical sequence will ensure the role of prey and landscape characteristics on the processes of predation are not over- or under-emphasized by decoupling kill sites from hunt paths, which will lead to a better mechanistic understanding of predation in heterogeneous environments.
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Affiliation(s)
- Heather M. McPhee
- Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Building, Edmonton, AB T6G 2E9, Canada
| | - Nathan F. Webb
- Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Building, Edmonton, AB T6G 2E9, Canada
| | - Evelyn H. Merrill
- Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Building, Edmonton, AB T6G 2E9, Canada
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McKenzie HW, Merrill EH, Spiteri RJ, Lewis MA. How linear features alter predator movement and the functional response. Interface Focus 2012; 2:205-16. [PMID: 22419990 PMCID: PMC3293201 DOI: 10.1098/rsfs.2011.0086] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/19/2011] [Indexed: 11/12/2022] Open
Abstract
In areas of oil and gas exploration, seismic lines have been reported to alter the movement patterns of wolves (Canis lupus). We developed a mechanistic first passage time model, based on an anisotropic elliptic partial differential equation, and used this to explore how wolf movement responses to seismic lines influence the encounter rate of the wolves with their prey. The model was parametrized using 5 min GPS location data. These data showed that wolves travelled faster on seismic lines and had a higher probability of staying on a seismic line once they were on it. We simulated wolf movement on a range of seismic line densities and drew implications for the rate of predator-prey interactions as described by the functional response. The functional response exhibited a more than linear increase with respect to prey density (type III) as well as interactions with seismic line density. Encounter rates were significantly higher in landscapes with high seismic line density and were most pronounced at low prey densities. This suggests that prey at low population densities are at higher risk in environments with a high seismic line density unless they learn to avoid them.
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Affiliation(s)
- Hannah W. McKenzie
- Centre for Mathematical Biology, Department of Mathematical and Statistical Sciences, 632 CAB, University of Alberta, Edmonton, Alberta, Canada T6G 2G1
| | - Evelyn H. Merrill
- Department of Biological Sciences, CW 405, Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | - Raymond J. Spiteri
- Department of Computer Science, 176 Thorvaldson Building, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, Canada S7N 5C9
| | - Mark A. Lewis
- Centre for Mathematical Biology, Department of Mathematical and Statistical Sciences, 632 CAB, University of Alberta, Edmonton, Alberta, Canada T6G 2G1
- Department of Biological Sciences, CW 405, Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
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Suckling DM, Tobin PC, McCullough DG, Herms DA. Combining tactics to exploit Allee effects for eradication of alien insect populations. JOURNAL OF ECONOMIC ENTOMOLOGY 2012; 105:1-13. [PMID: 22420248 DOI: 10.1603/ec11293] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Invasive species increasingly threaten ecosystems, food production, and human welfare worldwide. Hundreds of eradication programs have targeted a wide range of nonnative insect species to mitigate the economic and ecological impacts of biological invasions. Many such programs used multiple tactics to achieve this goal, but interactions between tactics have received little formal consideration, specifically as they interact with Allee dynamics. If a population can be driven below an Allee threshold, extinction becomes more probable because of factors such as the failure to find mates, satiate natural enemies, or successfully exploit food resources, as well as demographic and environmental stochasticity. A key implication of an Allee threshold is that the population can be eradicated without the need and expense of killing the last individuals. Some combinations of control tactics could interact with Allee dynamics to increase the probability of successful eradication. Combinations of tactics can be considered to have synergistic (greater efficiency in achieving extinction from the combination), additive (no improvement over single tactics alone), or antagonistic (reduced efficiency from the combination) effects on Allee dynamics. We highlight examples of combinations of tactics likely to act synergistically, additively, or antagonistically on pest populations. By exploiting the interacting effects of multiple tactics on Allee dynamics, the success and cost-effectiveness of eradication programs can be enhanced.
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Affiliation(s)
- David Maxwell Suckling
- The New Zealand Institute for Plant and Food Research Ltd., PB 4704, Christchurch, New Zealand.
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McLellan ML, Serrouya R, McLellan BN, Furk K, Heard DC, Wittmer HU. Implications of body condition on the unsustainable predation rates of endangered mountain caribou. Oecologia 2011; 169:853-60. [PMID: 22183706 DOI: 10.1007/s00442-011-2227-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 12/02/2011] [Indexed: 11/26/2022]
Affiliation(s)
- Michelle L McLellan
- Columbia Mountains Caribou Project, 4667 Carlson Rd., Nelson, BC, V1L 6X3, Canada
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McPhee HM, Webb NF, Merrill EH. Time-to-kill: measuring attack rates in a heterogenous landscape with multiple prey types. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.20203.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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Hebblewhite M, Merrill EH. Demographic balancing of migrant and resident elk in a partially migratory population through forage-predation tradeoffs. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19436.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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45
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Owen-Smith N, Chirima GJ, Macandza V, Le Roux E. Shrinking sable antelope numbers in Kruger National Park: what is suppressing population recovery? Anim Conserv 2011. [DOI: 10.1111/j.1469-1795.2011.00504.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- N. Owen-Smith
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Wits; South Africa
| | - G. J. Chirima
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Wits; South Africa
| | - V. Macandza
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Wits; South Africa
| | - E. Le Roux
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Wits; South Africa
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Wittmann MJ, Lewis MA, Young JD, Yan ND. Temperature-dependent Allee effects in a stage-structured model for Bythotrephes establishment. Biol Invasions 2011. [DOI: 10.1007/s10530-011-0074-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Habib TJ, Merrill EH, Pybus M, Coltman DW. Modelling landscape effects on density–contact rate relationships of deer in eastern Alberta: Implications for chronic wasting disease. Ecol Modell 2011. [DOI: 10.1016/j.ecolmodel.2011.05.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Whittington J, Hebblewhite M, DeCesare NJ, Neufeld L, Bradley M, Wilmshurst J, Musiani M. Caribou encounters with wolves increase near roads and trails: a time-to-event approach. J Appl Ecol 2011. [DOI: 10.1111/j.1365-2664.2011.02043.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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