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Williams S, Hebblewhite M, Martin H, Meyer C, Whittington J, Killeen J, Berg J, MacAulay K, Smolko P, Merrill EH. Predation risk drives long-term shifts in migratory behaviour and demography in a large herbivore population. J Anim Ecol 2024; 93:21-35. [PMID: 37982331 DOI: 10.1111/1365-2656.14022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 09/27/2023] [Indexed: 11/21/2023]
Abstract
Migration is an adaptive life-history strategy across taxa that helps individuals maximise fitness by obtaining forage and avoiding predation risk. The mechanisms driving migratory changes are poorly understood, and links between migratory behaviour, space use, and demographic consequences are rare. Here, we use a nearly 20-year record of individual-based monitoring of a large herbivore, elk (Cervus canadensis) to test hypotheses for changing patterns of migration in and adjacent to a large protected area in Banff National Park (BNP), Canada. We test whether bottom-up (forage quality) or top-down (predation risk) factors explained trends in (i) the proportion of individuals using 5 different migratory tactics, (ii) differences in survival rates of migratory tactics during migration and whilst on summer ranges, (iii) cause-specific mortality by wolves and grizzly bears, and (iv) population abundance. We found dramatic shifts in migration consistent with behavioural plasticity in individual choice of annual migratory routes. Shifts were inconsistent with exposure to the bottom-up benefits of migration. Instead, exposure to landscape gradients in predation risk caused by exploitation outside the protected area drove migratory shifts. Carnivore exploitation outside the protected area led to higher survival rates for female elk remaining resident or migrating outside the protected area. Cause-specific mortality aligned with exposure to predation risk along migratory routes and summer ranges. Wolf predation risk was higher on migratory routes than summer ranges of montane-migrant tactics, but wolf predation risk traded-off with heightened risk from grizzly bears on summer ranges. A novel eastern migrant tactic emerged following a large forest fire that enhanced forage in an area with lower predation risk outside of the protected area. The changes in migratory behaviour translated to population abundance, where abundance of the montane-migratory tactics declined over time. The presence of diverse migratory life histories maintained a higher total population abundance than would have been the case with only one migratory tactic in the population. Our study demonstrates the complex ways in which migratory populations change over time through behavioural plasticity and associated demographic consequences because of individuals balancing predation risk and forage trade-offs.
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Affiliation(s)
- S Williams
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - M Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - H Martin
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - C Meyer
- Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - J Whittington
- Banff National Park, Parks Canada, Banff, Alberta, Canada
| | - J Killeen
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - J Berg
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - K MacAulay
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - P Smolko
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- Department of Applied Zoology and Wildlife Management, Technical University in Zvolen, Zvolen, Slovakia
| | - E H Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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2
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Skoglund S, Whitlock R, Petersson E, Palm S, Leonardsson K. From spawner habitat selection to stock-recruitment: Implications for assessment. Ecol Evol 2022; 12:e9679. [PMID: 36590336 PMCID: PMC9797469 DOI: 10.1002/ece3.9679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 11/30/2022] [Accepted: 12/09/2022] [Indexed: 12/29/2022] Open
Abstract
The relationship between the spawning stock size and subsequent number of recruits is a central concept in fisheries ecology. The influence of habitat selection of spawning individuals on the stock-recruitment relationship is poorly known. Here we explore how each of four different spawner behaviors might influence the stock-recruitment relationship and estimates of its parameters in the two most commonly used stock-recruitment functions (Beverton-Holt and Ricker). Using simulated stock-recruitment data generated by four different spawner behaviors applied to multiple discrete habitats, we show that when spawners were distributed proportionally to local carrying capacities, there was small or no bias in estimated recruitment and stock-recruitment parameters. For an ideal free distribution of spawners, larger bias in the estimates of recruitment and stock-recruitment parameters was obtained, whereas a random and a stepwise spawner behavior introduced the largest bias. Using stock-recruitment data corresponding to a "realistic" range of population densities and adding measurement error (20%-60%) to the simulated stock-recruitment data generated larger variation in the estimation bias than what was introduced by the spawner behavior. Thus, for exploited stocks at low population density and where spawning stock size and recruitment cannot be observed perfectly, partial observation of the possible spawner abundance range and measurement error might be of higher concern for management.
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Affiliation(s)
- Stefan Skoglund
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Rebecca Whitlock
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Erik Petersson
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Stefan Palm
- Department of Aquatic Resources, Institute of Freshwater ResearchSwedish University of Agricultural SciencesDrottiningholmSweden
| | - Kjell Leonardsson
- Department of Wildlife, Fish and Environmental StudiesSwedish University of Agricultural SciencesUmeåSweden
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3
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Martin HW, Hebblewhite M, Merrill EH. Large herbivores in a partially migratory population search for the ideal free home. Ecology 2022; 103:e3652. [PMID: 35084736 PMCID: PMC10162400 DOI: 10.1002/ecy.3652] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 09/10/2021] [Accepted: 10/26/2021] [Indexed: 11/07/2022]
Abstract
Migration is a tactic used across taxa to access resources in temporally heterogenous landscapes. Populations that migrate can attain higher abundances because such movements allow access to higher quality resources, or reduction in predation risk resulting in increased fitness. However, most migratory species occur in partially migratory populations, a mix of migratory and non-migratory individuals. It is thought that the portion of migrants in a partial migration population is maintained either through 1) a population-level evolutionary stable state where counteracting density-dependent vital rates act on migrants and residents to balance fitness, or 2) conditional migration, where the propensity to migrate is influenced by the individual's state. However, in many respects, migration is also a form of habitat selection and the proportion of migrants and residents may be the result of density-dependent habitat selection. Here, we test whether the theory of Ideal Free Distribution (IFD) can explain the coexistence of different migratory tactics in a partially migratory population. IFD predicts individuals exhibit density-dependent vital rates and select different migratory tactics to maximize individual fitness resulting in equal fitness (λ) between tactics. We tested the predictions of IFD in a partially migratory elk population that declined by 70% with 19 years of demographic data and migratory tactic switching rates from >300 individuals. We found evidence of density dependence for resident pregnancy and adult female survival providing a fitness incentive to switch tactics. Despite differences in vital rates between migratory tactics, mean λ (fitness) was equal. However, as predicted by the IFD, individuals switched tactics toward those of higher fitness. Our analysis reveals that partial migration may be driven by tactic selection that follows the ideal free distribution. These findings reinforce that migration across taxa may be a polymorphic behavior in large herbivores where migratory tactic selection is determined by differential costs and benefits, mediated by density-dependence.
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Affiliation(s)
- Hans W Martin
- Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - Mark Hebblewhite
- Wildlife Biology Program, W.A. Franke College of Forestry and Conservation, University of Montana, Missoula, Montana, USA
| | - Evelyn H Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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4
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Abstract
Abstract
Under the ideal free distribution (IFD), the number of organisms competing for a resource at different sites is proportional to the resource distribution among sites. The ideal free distribution of competitors in a heterogeneous environment often predicts habitat matching, where the relative number of individuals using any two patches matches the relative availability of resources in those same two patches. If a resource is scarce, access might be restricted to individuals with high resource holding potential, resulting in deviation from the IFD. The distribution of animals may also deviate from the IFD in the case of resource abundance, when social attraction or preference for specific locations rather than competition may determine distribution. While it was originally developed to explain habitat choice, we apply the habitat matching rule to microscale foraging decisions. We show that chickens feeding from two nondepleting feeders distribute proportionally to feeder space under intermediate levels of competition. However, chicken distribution between the feeders deviates from the IFD when feeder space is limited and competition high. Further, despite decreasing aggression with increasing feeder space, deviation from IFD is also observed under an excess supply of feeder space, indicating different mechanisms responsible for deviations from the IFD. Besides demonstrating IFD sensitivity to competition, these findings highlight IFD’s potential as a biological basis for determining minimal resource requirements in animal housing.
Significance statement
The ideal free distribution (IFD) predicts how animals ought to distribute themselves within a habitat in order to maximize their payoff. Recent studies, however, have questioned the validity of the IFD concept following anomalous results. We studied the IFD in chickens by systematically varying the amount and distribution of space at two feed troughs. We show that when tested over a sufficiently large range, the distribution of birds depends on the overall resource availability. Furthermore, behavioral data suggest that distinctly different mechanisms account for deviations from the IFD at shortage and excess supply of feeder space, respectively.
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5
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Monk CT, Chéret B, Czapla P, Hühn D, Klefoth T, Eschbach E, Hagemann R, Arlinghaus R. Behavioural and fitness effects of translocation to a novel environment: Whole‐lake experiments in two aquatic top predators. J Anim Ecol 2020; 89:2325-2344. [DOI: 10.1111/1365-2656.13298] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Accepted: 06/04/2020] [Indexed: 01/14/2023]
Affiliation(s)
- Christopher T. Monk
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - Bernard Chéret
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - Philipp Czapla
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - Daniel Hühn
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | | | - Erik Eschbach
- Thünen Institute of Fisheries Ecology Bremerhaven Germany
| | - Robert Hagemann
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
| | - Robert Arlinghaus
- Department of Biology and Ecology of FishesLeibniz‐Institute of Freshwater Ecology and Inland Fisheries Berlin Germany
- Faculty of Life Sciences and Integrative Research Institute for the Transformation of Human‐Environmental Systems Humboldt‐Universität zu Berlin Berlin Germany
- Division of Integrative Fisheries Management Department of Crop and Animal Sciences Faculty of Life Science Humboldt‐Universität zu Berlin Berlin Germany
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6
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O'Neil ST, Vucetich JA, Beyer DE, Hoy SR, Bump JK. Territoriality drives preemptive habitat selection in recovering wolves: Implications for carnivore conservation. J Anim Ecol 2020; 89:1433-1447. [PMID: 32145068 DOI: 10.1111/1365-2656.13199] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 02/05/2020] [Indexed: 11/29/2022]
Abstract
According to the ideal-free distribution (IFD), individuals within a population are free to select habitats that maximize their chances of success. Assuming knowledge of habitat quality, the IFD predicts that average fitness will be approximately equal among individuals and between habitats, while density varies, implying that habitat selection will be density dependent. Populations are often assumed to follow an IFD, although this assumption is rarely tested with empirical data, and may be incorrect when territoriality indicates habitat selection tactics that deviate from the IFD (e.g. ideal-despotic distribution or ideal-preemptive distribution). When territoriality influences habitat selection, species' density will not directly reflect components of fitness such as reproductive success or survival. In such cases, assuming an IFD can lead to false conclusions about habitat quality. We tested theoretical models of density-dependent habitat selection on a species known to exhibit territorial behaviour in order to determine whether commonly applied habitat models are appropriate under these circumstances. We combined long-term radiotelemetry and census data from grey wolves Canis lupus in the Upper Peninsula of Michigan, USA to relate spatiotemporal variability in wolf density to underlying classifications of habitat within a hierarchical state-space modelling framework. We then iteratively applied isodar analysis to evaluate which distribution of habitat selection best described this recolonizing wolf population. The wolf population in our study expanded by >1,000% during our study (~50 to >600 individuals), and density-dependent habitat selection was most consistent with the ideal-preemptive distribution, as opposed to the ideal-free or ideal-despotic alternatives. Population density of terrestrial carnivores may not be positively correlated with the fitness value of their habitats, and density-dependent habitat selection patterns may help to explain complex predator-prey dynamics and cascading indirect effects. Source-sink population dynamics appear likely when species exhibit rapid growth and occupy interspersed habitats of contrasting quality. These conditions are likely and have implications for large carnivores in many systems, such as areas in North America and Europe where large predator species are currently recolonizing their former ranges.
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Affiliation(s)
- Shawn T O'Neil
- School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton, MI, USA
| | - John A Vucetich
- School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton, MI, USA
| | - Dean E Beyer
- School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton, MI, USA.,Wildlife Division, Michigan Department of Natural Resources, 1990 U.S. Hwy 41 So, Marquette, MI, USA
| | - Sarah R Hoy
- School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton, MI, USA
| | - Joseph K Bump
- Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, St. Paul, MN, USA
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7
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The geometry of reaction norms yields insights on classical fitness functions for Great Lakes salmon. PLoS One 2020; 15:e0228990. [PMID: 32176717 PMCID: PMC7075576 DOI: 10.1371/journal.pone.0228990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 01/28/2020] [Indexed: 11/28/2022] Open
Abstract
Life history theory examines how characteristics of organisms, such as age and size at maturity, may vary through natural selection as evolutionary responses that optimize fitness. Here we ask how predictions of age and size at maturity differ for the three classical fitness functions–intrinsic rate of natural increase r, net reproductive rate R0, and reproductive value Vx−for semelparous species. We show that different choices of fitness functions can lead to very different predictions of species behavior. In one’s efforts to understand an organism’s behavior and to develop effective conservation and management policies, the choice of fitness function matters. The central ingredient of our approach is the maturation reaction norm (MRN), which describes how optimal age and size at maturation vary with growth rate or mortality rate. We develop a practical geometric construction of MRNs that allows us to include different growth functions (linear growth and nonlinear von Bertalanffy growth in length) and develop two-dimensional MRNs useful for quantifying growth-mortality trade-offs. We relate our approach to Beverton-Holt life history invariants and to the Stearns-Koella categorization of MRNs. We conclude with a detailed discussion of life history parameters for Great Lakes Chinook Salmon and demonstrate that age and size at maturity are consistent with predictions using R0 (but not r or Vx) as the underlying fitness function.
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8
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D'Agata A. Dynamics of spatially dispersed population under ideal free distribution. J Theor Biol 2020; 486:110071. [PMID: 31704312 DOI: 10.1016/j.jtbi.2019.110071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/27/2019] [Accepted: 11/02/2019] [Indexed: 10/25/2022]
Affiliation(s)
- Antonio D'Agata
- Department of Political and Social Science, University of Catania, Via Vittorio Emanuele 8, 95131 Catania, Italy.
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9
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Spatial and temporal patterns of a pulsed resource dynamically drive the distribution of specialist herbivores. Sci Rep 2019; 9:17787. [PMID: 31780724 PMCID: PMC6882897 DOI: 10.1038/s41598-019-54297-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/31/2019] [Indexed: 11/14/2022] Open
Abstract
Patterns and drivers of the spatio-temporal distribution of herbivores are key elements of their ecological and evolutionary impacts on plant populations. Herbivore spatial distributions may be influenced by increased (RCH: resource concentration hypothesis) or decreased (RDH: resource dilution hypothesis) resource densities, but the effect of temporal variations in resource densities on such distributions remains poorly documented. We used a survey of a masting tree species and its seed predators in Southeastern France to address the effect of a host’s pulsed resource on the spatio-temporal distributions of highly specialized insect herbivores feeding on seeds. Variations in both resource and seed predator densities were assessed by estimating seed production and seed infestation rates in focus trees during 10 consecutive years. We found increasing seed infestation rates with decreasing host tree densities in years of low seed production, indicating a RDH pattern of seed predators. However, such pattern was not persistent in years of high seed production during which seed infestation rates did not depend on host tree densities. We showed that temporal variations in resource density can lead to transience of seed predator spatial distribution. This study highlights how predictions of plant-herbivore interactions in natural ecosystems may rely on temporal components underlying RCH and RDH hypotheses.
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10
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Swain DP, Benoît HP, Hammill MO, Sulikowski JA. Risk of extinction of a unique skate population due to predation by a recovering marine mammal. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01921. [PMID: 31059188 DOI: 10.1002/eap.1921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 01/02/2019] [Accepted: 02/14/2019] [Indexed: 06/09/2023]
Abstract
Benefitting from reduced harvesting and an end to culling, many marine mammals are now recovering from past overexploitation. These recoveries represent important conservation successes but present a serious conservation problem when the recovering mammals are predators of species of conservation concern. Here, we examine the role of predation by recovering grey seals (Halichoerus grypus) in the near-extinction of a unique skate population in the southern Gulf of St. Lawrence (sGSL) in Atlantic Canada. Winter skate (Leucoraja ocellata) in the sGSL are distinct from winter skate elsewhere and may represent an endemic species. Their adult abundance has declined by 98% since 1980, and these skates are now detectable in only a small fraction of their former range. Population modeling indicates that the ongoing collapse of this population is due to increases in the natural mortality of adults. Based on model projections, this population would be extinct by mid-century if its current rate of productivity were to persist. A second population model incorporated predation by grey seals. Model estimates of skate consumption by seals were consistent with historical and recent estimates of the contribution of skates to grey seal diets. The estimated consumption accounted for the increases in the natural mortality of adult skates. A Type III functional response for grey seals preying on winter skate emerged from the model results. This indicates that, when skate abundance is very low, grey seals are expected to switch to alternate prey, resulting in declines in the mortality of skates due to predation. Consequently, contrary to projections at current productivity, winter skate are expected to be trapped at very low abundance in a "predator pit" instead of declining to extinction. Nonetheless, extinction risk would remain very high at the very small population size in the predator pit. Our results emphasize the need for an ecosystem-based approach to the management of living resources in this ecosystem.
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Affiliation(s)
- Douglas P Swain
- Gulf Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5030, Moncton, New Brunswick, E1C 9B6, Canada
| | - Hugues P Benoît
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, P.O. Box 1000, Mont-Joli, Quebec, G5H 3Z4, Canada
| | - Mike O Hammill
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, P.O. Box 1000, Mont-Joli, Quebec, G5H 3Z4, Canada
| | - James A Sulikowski
- Arthur P. Girard Marine Science Department, University of New England, 11 Hills Beach Road, Biddeford, Maine, 04005, USA
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11
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Street GM, Erovenko IV, Rowell JT. Dynamical facilitation of the ideal free distribution in nonideal populations. Ecol Evol 2018; 8:2471-2481. [PMID: 29531668 PMCID: PMC5838054 DOI: 10.1002/ece3.3811] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 11/29/2017] [Accepted: 12/06/2017] [Indexed: 11/25/2022] Open
Abstract
The ideal free distribution (IFD) requires that individuals can accurately perceive density-dependent habitat quality, while failure to discern quality differences below a given perception threshold results in distributions approaching spatial uniformity. Here, we investigate the role of population growth in restoring a nonideal population to the IFD. We place a simple model of discrete patch choice under limits to the resolution by which patch quality is perceived and include population growth driven by that underlying quality. Our model follows the population's distribution through both breeding and dispersal seasons when perception limits differ in their likely influence. We demonstrate that populations of perception limited movers can approximate an IFD provided sufficient population growth; however, the emergent IFD would be temporally inconstant and correspond to reproductive events. The time to emergence of the IFD during breeding is shorter under exponential growth than under logistic growth. The IFD during early colonization of a community persists longer when more patches are available to individuals. As the population matures and dispersal becomes increasingly random, there is an oscillation in the observance of IFD, with peaks most closely approximating the IFD occurring immediately after reproductive events, and higher reproductive rates producing distributions closer to the IFD.
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Affiliation(s)
- Garrett M. Street
- Department of Wildlife, Fisheries, and AquacultureMississippi State UniversityMississippi StateMSUSA
| | - Igor V. Erovenko
- Department of Mathematics and StatisticsUniversity of North Carolina at GreensboroGreensboroNCUSA
| | - Jonathan T. Rowell
- Department of Mathematics and StatisticsUniversity of North Carolina at GreensboroGreensboroNCUSA
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12
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Maberly SC, Ciar D, Elliott JA, Jones ID, Reynolds CS, Thackeray SJ, Winfield IJ. From Ecological Informatics to the Generation of Ecological Knowledge: Long-Term Research in the English Lake District. ECOL INFORM 2018. [DOI: 10.1007/978-3-319-59928-1_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Halliday WD, Blouin‐Demers G. Can temperature modify the strength of density‐dependent habitat selection in ectotherms? A test with red flour beetles. J Zool (1987) 2017. [DOI: 10.1111/jzo.12510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- W. D. Halliday
- Department of Biology University of Ottawa Ottawa ON Canada
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14
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Huntsman BM, Falke JA, Savereide JW, Bennett KE. The role of density-dependent and -independent processes in spawning habitat selection by salmon in an Arctic riverscape. PLoS One 2017; 12:e0177467. [PMID: 28531202 PMCID: PMC5439693 DOI: 10.1371/journal.pone.0177467] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 04/27/2017] [Indexed: 11/18/2022] Open
Abstract
Density-dependent (DD) and density-independent (DI) habitat selection is strongly linked to a species’ evolutionary history. Determining the relative importance of each is necessary because declining populations are not always the result of altered DI mechanisms but can often be the result of DD via a reduced carrying capacity. We developed spatially and temporally explicit models throughout the Chena River, Alaska to predict important DI mechanisms that influence Chinook salmon spawning success. We used resource-selection functions to predict suitable spawning habitat based on geomorphic characteristics, a semi-distributed water-and-energy balance hydrologic model to generate stream flow metrics, and modeled stream temperature as a function of climatic variables. Spawner counts were predicted throughout the core and periphery spawning sections of the Chena River from escapement estimates (DD) and DI variables. Additionally, we used isodar analysis to identify whether spawners actively defend spawning habitat or follow an ideal free distribution along the riverscape. Aerial counts were best explained by escapement and reference to the core or periphery, while no models with DI variables were supported in the candidate set. Furthermore, isodar plots indicated habitat selection was best explained by ideal free distributions, although there was strong evidence for active defense of core spawning habitat. Our results are surprising, given salmon commonly defend spawning resources, and are likely due to competition occurring at finer spatial scales than addressed in this study.
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Affiliation(s)
- Brock M. Huntsman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America
- * E-mail:
| | - Jeffrey A. Falke
- U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America
| | - James W. Savereide
- Alaska Department of Fish and Game, Division of Sport Fish, Fairbanks, Alaska, United States of America
| | - Katrina E. Bennett
- Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
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15
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Differential fitness in field and forest explains density-independent habitat selection by gartersnakes. Oecologia 2016; 181:841-51. [PMID: 27016079 DOI: 10.1007/s00442-016-3605-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 03/07/2016] [Indexed: 10/22/2022]
Abstract
The ideal free distribution concept predicts that organisms will distribute themselves between habitats in a density-dependent manner so that individuals, on average, achieve the same fitness in each habitat. In ectotherms, environmental temperature has a strong impact on fitness, but temperature is not depletable and thus not density dependent. Can density-dependent habitat selection occur in ectotherms when habitats differ in thermal quality? We used an observational study of habitat selection by small snakes in field and forest, followed by manipulative habitat selection and fitness experiments with common gartersnakes in enclosures in field and forest to test this hypothesis. Snakes were much more abundant in the field, the habitat with superior thermal quality, than in the forest. Gartersnakes in our controlled experiment only used the forest habitat when snake density was highest and when food was more abundant in the forest; habitat selection was largely density independent, although there was weak evidence of density dependence. No female gartersnake gave birth in the forest enclosures, whereas half of the females gave birth in the field enclosures. Growth rates of females were higher in field than in forest enclosures. Overall, our data indicate that temperature appears to be the most important factor driving the habitat selection of gartersnakes, likely because temperature was more limiting than food in our study system. Snakes, or at least temperate snakes, may naturally exist at population densities low enough that they do not exhibit density-dependent habitat selection.
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16
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Eggeman SL, Hebblewhite M, Bohm H, Whittington J, Merrill EH. Behavioural flexibility in migratory behaviour in a long-lived large herbivore. J Anim Ecol 2016; 85:785-97. [PMID: 26790111 DOI: 10.1111/1365-2656.12495] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 11/27/2015] [Indexed: 11/30/2022]
Abstract
Migratory animals are predicted to enhance lifetime fitness by obtaining higher quality forage and/or reducing predation risk compared to non-migratory conspecifics. Despite evidence for behavioural flexibility in other taxa, previous research on large mammals has often assumed that migratory behaviour is a fixed behavioural trait. Migratory behaviour may be plastic for many species, although few studies have tested for individual-level flexibility using long-term monitoring of marked individuals, especially in large mammals such as ungulates. We tested variability in individual migratory behaviour using a 10-year telemetry data set of 223 adult female elk (Cervus elaphus) in the partially migratory Ya Ha Tinda population in Alberta, Canada. We used net squared displacement (NSD) to classify migratory strategy for each individual elk-year. Individuals switched between migrant and resident strategies at a mean rate of 15% per year, and migrants were more likely to switch than residents. We then tested how extrinsic (climate, elk/wolf abundance) and intrinsic (age) factors affected the probability of migrating, and, secondly, the decision to switch between migratory strategies. Over 630 individual elk-years, the probability of an individual elk migrating increased following a severe winter, in years of higher wolf abundance, and with increasing age. At an individual elk level, we observed 148 switching events of 430 possible transitions in elk monitored at least 2 years. We found switching was density-dependent, where migrants switched to a resident strategy at low elk abundance, but residents switched more to a migrant strategy at high elk abundance. Precipitation during the previous summer had a weak carryover effect, with migrants switching slightly more following wetter summers, whereas residents showed the opposite pattern. Older migrant elk rarely switched, whereas resident elk switched more frequently to migrate at older ages. Our results show migratory behaviour in ungulates is an individually variable trait that can respond to intrinsic, environmental and density-dependent forces. Different strategies had opposing responses to density-dependent and intrinsic drivers, providing a stabilizing mechanism for the maintenance of partial migration and demographic fitness in this population.
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Affiliation(s)
- Scott L Eggeman
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, MT, 59812, USA
| | - Mark Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, MT, 59812, USA
| | - Holger Bohm
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E9
| | - Jesse Whittington
- Resource Conservation, Parks Canada, Banff National Park, Banff, Alberta, Canada
| | - Evelyn H Merrill
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada, T6G 2E9
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17
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Edeline E, Groth A, Cazelles B, Claessen D, Winfield IJ, Ohlberger J, Asbjørn Vøllestad L, Stenseth NC, Ghil M. Pathogens trigger top-down climate forcing on ecosystem dynamics. Oecologia 2016; 181:519-32. [DOI: 10.1007/s00442-016-3575-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 01/24/2016] [Indexed: 11/24/2022]
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18
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Barth CC, Anderson WG. Factors influencing spatial distribution and growth of juvenile lake sturgeon (Acipenser fulvescens). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2015-0058] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Understanding biotic and abiotic factors that influence spatial distribution patterns, condition factor, and growth of lotic fish species within river impoundments is essential for the development of effective management and conservation strategies. This study aimed to compare relative abundance, condition factor, and growth rate of juvenile lake sturgeon (Acipenser fulvescens Rafinesque, 1817) among eight sections of a 41 km long impoundment of the Winnipeg River, Manitoba, Canada. Relative abundance of juvenile lake sturgeon, as measured by catch per unit effort (CPUE), was 3–6 times greater in the two farthest upstream sections when compared with the five farthest downstream sections. Growth in length was slowest for individuals captured in the two farthest upstream sections, moderate in the third section, and highest in the fourth section, with individuals from the fourth section attaining lengths approximately double those from the two farthest upstream sections by age 6. Condition factor varied among sections of the impoundment in a pattern similar to that observed for growth. Given similarities in many environmental factors such as water temperature and water chemistry among sections of this study area, our results provide important insight into how abiotic and biotic factors, combined with behavioural characteristics of this species, may influence distribution patterns and growth of juvenile lake sturgeon within river impoundments.
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Affiliation(s)
- Cameron C. Barth
- North/South Consultants Inc., 83 Scurfield Boulevard, Winnipeg, MB R3Y 1G4, Canada
| | - W. Gary Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
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19
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Napolitano C, Díaz D, Sanderson J, Johnson WE, Ritland K, Ritland CE, Poulin E. Reduced Genetic Diversity and Increased Dispersal in Guigna (Leopardus guigna) in Chilean Fragmented Landscapes. J Hered 2015; 106 Suppl 1:522-36. [PMID: 26245787 DOI: 10.1093/jhered/esv025] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Landscape fragmentation is often a major cause of species extinction as it can affect a wide variety of ecological processes. The impact of fragmentation varies among species depending on many factors, including their life-history traits and dispersal abilities. Felids are one of the groups most threatened by fragmented landscapes because of their large home ranges, territorial behavior, and low population densities. Here, we model the impacts of habitat fragmentation on patterns of genetic diversity in the guigna (Leopardus guigna), a small felid that is closely associated with the heavily human-impacted temperate rainforests of southern South America. We assessed genetic variation in 1798 base pairs of mitochondrial DNA sequences, 15 microsatellite loci, and 2 sex chromosome genes and estimated genetic diversity, kinship, inbreeding, and dispersal in 38 individuals from landscapes with differing degrees of fragmentation on Chiloé Island in southern Chile. Increased fragmentation was associated with reduced genetic diversity, but not with increased kinship or inbreeding. However, in fragmented landscapes, there was a weaker negative correlation between pairwise kinship and geographic distance, suggesting increased dispersal distances. These results highlight the importance of biological corridors to maximize connectivity in fragmented landscapes and contribute to our understanding of the broader genetic consequences of habitat fragmentation, especially for forest-specialist carnivores.
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Affiliation(s)
- Constanza Napolitano
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland).
| | - Diego Díaz
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
| | - Jim Sanderson
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
| | - Warren E Johnson
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
| | - Kermit Ritland
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
| | - Carol E Ritland
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
| | - Elie Poulin
- From the Laboratorio de Ecología Molecular, Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile (Napolitano and Poulin); Departamento de Ciencias Ambientales y Recursos Naturales, Facultad de Ciencias Agronómicas, Universidad de Chile, Santiago, Chile (Díaz); Small Wild Cat Conservation Foundation, Campbell, CA (Sanderson); Smithsonian Conservation Biology Institute, Front Royal, VA (Johnson); and Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, BC, Canada (K. Ritland and CE. Ritland)
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Tardy O, Massé A, Pelletier F, Fortin D. Resampling method for applying density-dependent habitat selection theory to wildlife surveys. PLoS One 2015; 10:e0128238. [PMID: 26042998 PMCID: PMC4456250 DOI: 10.1371/journal.pone.0128238] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 04/24/2015] [Indexed: 11/18/2022] Open
Abstract
Isodar theory can be used to evaluate fitness consequences of density-dependent habitat selection by animals. A typical habitat isodar is a regression curve plotting competitor densities in two adjacent habitats when individual fitness is equal. Despite the increasing use of habitat isodars, their application remains largely limited to areas composed of pairs of adjacent habitats that are defined a priori. We developed a resampling method that uses data from wildlife surveys to build isodars in heterogeneous landscapes without having to predefine habitat types. The method consists in randomly placing blocks over the survey area and dividing those blocks in two adjacent sub-blocks of the same size. Animal abundance is then estimated within the two sub-blocks. This process is done 100 times. Different functional forms of isodars can be investigated by relating animal abundance and differences in habitat features between sub-blocks. We applied this method to abundance data of raccoons and striped skunks, two of the main hosts of rabies virus in North America. Habitat selection by raccoons and striped skunks depended on both conspecific abundance and the difference in landscape composition and structure between sub-blocks. When conspecific abundance was low, raccoons and striped skunks favored areas with relatively high proportions of forests and anthropogenic features, respectively. Under high conspecific abundance, however, both species preferred areas with rather large corn-forest edge densities and corn field proportions. Based on random sampling techniques, we provide a robust method that is applicable to a broad range of species, including medium- to large-sized mammals with high mobility. The method is sufficiently flexible to incorporate multiple environmental covariates that can reflect key requirements of the focal species. We thus illustrate how isodar theory can be used with wildlife surveys to assess density-dependent habitat selection over large geographic extents.
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Affiliation(s)
- Olivia Tardy
- Centre d’Étude de la Forêt and Département de biologie, Université Laval, Québec, Québec, Canada
| | - Ariane Massé
- Direction de la biodiversité et des maladies de la faune, Direction générale de l’expertise sur la faune et ses habitats, Ministère des Forêts, de la Faune et des Parcs, Québec, Québec, Canada
| | - Fanie Pelletier
- Canada Research Chair in Evolutionary Demography and Conservation, Département de biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Daniel Fortin
- Centre d’Étude de la Forêt and Département de biologie, Université Laval, Québec, Québec, Canada
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21
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Tibblin P, Forsman A, Koch-Schmidt P, Nordahl O, Johannessen P, Nilsson J, Larsson P. Evolutionary divergence of adult body size and juvenile growth in sympatric subpopulations of a top predator in aquatic ecosystems. Am Nat 2015; 186:98-110. [PMID: 26098342 DOI: 10.1086/681597] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Evolutionary theory predicts that different selective regimes may contribute to divergent evolution of body size and growth rate among populations, but most studies have focused on allopatric populations. Here, we studied five sympatric subpopulations of anadromous northern pike (Esox lucius) in the Baltic Sea subjected to allopatric habitats for a short period of their life cycle due to homing behavior. We report differences in adult body size among subpopulations that were in part due to variation in growth rate. Body size of emigrating juveniles also differed among subpopulations, and differences remained when individuals were reared in a common environment, thus indicating evolutionary divergence among subpopulations. Furthermore, a QST-FST comparison indicated that differences had evolved due to divergent selection rather than genetic drift, possibly in response to differences in selective mortality among spawning habitats during the allopatric life stage. Adult and juvenile size were negatively correlated across subpopulations, and reconstruction of growth trajectories of adult fishes suggested that body size differences developed gradually and became accentuated throughout the first years of life. These results represent rare evidence that sympatric subpopulations can evolve differences in key life-history traits despite being subjected to allopatric habitats during only a very short fraction of their life.
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Affiliation(s)
- Petter Tibblin
- Ecology and Evolution in Microbial Model Systems (EEMiS), Department of Biology and Environmental Science, Linnaeus University, SE-391 82 Kalmar, Sweden
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22
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Pagel T, Bekkevold D, Pohlmeier S, Wolter C, Arlinghaus R. Thermal and maternal environments shape the value of early hatching in a natural population of a strongly cannibalistic freshwater fish. Oecologia 2015; 178:951-65. [PMID: 25894093 DOI: 10.1007/s00442-015-3301-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 03/16/2015] [Indexed: 11/24/2022]
Affiliation(s)
- Thilo Pagel
- Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany,
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23
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Robertson A, McDonald RA, Delahay RJ, Kelly SD, Bearhop S. Resource availability affects individual niche variation and its consequences in group-living European badgers Meles meles. Oecologia 2015; 178:31-43. [PMID: 25656581 DOI: 10.1007/s00442-014-3202-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 12/15/2014] [Indexed: 11/25/2022]
Abstract
Although intra-population variation in niches is a widespread phenomenon with important implications for ecology, evolution and management of a range of animal species, the causes and consequences of this variation remain poorly understood. We used stable isotope analysis to characterise foraging niches and to investigate the causes and consequences of individual niche variation in the European badger, a mustelid mammal that lives in territorial social groups, but forages alone. We found that the degree of individual niche variation within social groups was negatively related to the availability of farmland habitats, which represent an important foraging habitat for badgers; and was positively related to territory size, supporting the idea that resource limitation and ecological opportunity lead to increased individual specialisation. We also found that the degree of individual specialisation related to an individual's body condition and that this effect varied with ecological context; such that specialisation had a stronger positive relationship with body condition in social groups with reduced availability of key farmland habitats. Body condition was also related to the utilisation of specific resources (woodland invertebrates), but again this relationship varied with the availability of farmland foraging habitats. This study supports the idea that resource availability plays an important role in determining patterns of individual niche variation, and identifies the potential adaptive consequences of specialised foraging strategies.
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Affiliation(s)
- Andrew Robertson
- Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall, TR10 9EZ, UK,
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24
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Křivan V, Jana D. Effects of animal dispersal on harvesting with protected areas. J Theor Biol 2015; 364:131-8. [DOI: 10.1016/j.jtbi.2014.09.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 09/02/2014] [Accepted: 09/06/2014] [Indexed: 12/01/2022]
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25
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Falcy MR. Density-dependent habitat selection of spawning Chinook salmon: broad-scale evidence and implications. J Anim Ecol 2014; 84:545-53. [DOI: 10.1111/1365-2656.12297] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 09/21/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew R. Falcy
- Oregon Department of Fish and Wildlife; 4034 Fairview Industrial Dr SE Salem OR 97302 USA
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26
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Tardy O, Massé A, Pelletier F, Mainguy J, Fortin D. Density-dependent functional responses in habitat selection by two hosts of the raccoon rabies virus variant. Ecosphere 2014. [DOI: 10.1890/es14-00197.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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27
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Protected polymorphisms and evolutionary stability of patch-selection strategies in stochastic environments. J Math Biol 2014; 71:325-59. [PMID: 25151369 DOI: 10.1007/s00285-014-0824-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/07/2014] [Indexed: 10/24/2022]
Abstract
We consider a population living in a patchy environment that varies stochastically in space and time. The population is composed of two morphs (that is, individuals of the same species with different genotypes). In terms of survival and reproductive success, the associated phenotypes differ only in their habitat selection strategies. We compute invasion rates corresponding to the rates at which the abundance of an initially rare morph increases in the presence of the other morph established at equilibrium. If both morphs have positive invasion rates when rare, then there is an equilibrium distribution such that the two morphs coexist; that is, there is a protected polymorphism for habitat selection. Alternatively, if one morph has a negative invasion rate when rare, then it is asymptotically displaced by the other morph under all initial conditions where both morphs are present. We refine the characterization of an evolutionary stable strategy for habitat selection from Schreiber (Am Nat 180:17-34, 2012) in a mathematically rigorous manner. We provide a necessary and sufficient condition for the existence of an ESS that uses all patches and determine when using a single patch is an ESS. We also provide an explicit formula for the ESS when there are two habitat types. We show that adding environmental stochasticity results in an ESS that, when compared to the ESS for the corresponding model without stochasticity, spends less time in patches with larger carrying capacities and possibly makes use of sink patches, thereby practicing a spatial form of bet hedging.
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28
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Halliday WD, Blouin-Demers G. Red flour beetles balance thermoregulation and food acquisition via density-dependent habitat selection. J Zool (1987) 2014. [DOI: 10.1111/jzo.12168] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W. D. Halliday
- Department of Biology; University of Ottawa; Ottawa ON Canada
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29
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Nicolai CA, Sedinger JS, Ward DH, Boyd WS. Spatial variation in life-history trade-offs results in an ideal free distribution in Black Brant Geese. Ecology 2014; 95:1323-31. [DOI: 10.1890/13-0860.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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30
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Goldberg JF, Hebblewhite M, Bardsley J. Consequences of a refuge for the predator-prey dynamics of a wolf-elk system in Banff National Park, Alberta, Canada. PLoS One 2014; 9:e91417. [PMID: 24670632 PMCID: PMC3966774 DOI: 10.1371/journal.pone.0091417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 02/12/2014] [Indexed: 11/18/2022] Open
Abstract
Refugia can affect predator-prey dynamics via movements between refuge and non-refuge areas. We examine the influence of a refuge on population dynamics in a large mammal predator-prey system. Wolves (Canis lupus) have recolonized much of their former range in North America, and as a result, ungulate prey have exploited refugia to reduce predation risk with unknown impacts on wolf-prey dynamics. We examined the influence of a refuge on elk (Cervus elaphus) and wolf population dynamics in Banff National Park. Elk occupy the Banff townsite with little predation, whereas elk in the adjoining Bow Valley experience higher wolf predation. The Banff refuge may influence Bow Valley predator-prey dynamics through source-sink movements. To test this hypothesis, we used 26 years of wolf and elk population counts and the Delayed Rejection Adaptive Metropolis Markov chain Monte Carlo method to fit five predator-prey models: 1) with no source-sink movements, 2) with elk density-dependent dispersal from the refuge to the non-refuge, 3) with elk predation risk avoidance movements from the non-refuge to the refuge, 4) with differential movement rates between refuge and non-refuge, and 5) with short-term, source-sink wolf movements. Model 1 provided the best fit of the data, as measured by Akaike Information Criterion (AIC). In the top model, Banff and Bow Valley elk had median growth rates of 0.08 and 0.03 (95% credibility intervals [CIs]: 0.027-0.186 and 0.001-0.143), respectively, Banff had a median carrying capacity of 630 elk (95% CI: 471.9-2676.9), Bow Valley elk had a median wolf encounter rate of 0.02 (95% CI: 0.013-0.030), and wolves had a median death rate of 0.23 (95% CI: 0.146-0.335) and a median conversion efficiency of 0.07 (95% CI: 0.031-0.124). We found little evidence for potential source-sink movements influencing the predator-prey dynamics of this system. This result suggests that the refuge was isolated from the non-refuge.
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Affiliation(s)
- Joshua F. Goldberg
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America
| | - Mark Hebblewhite
- Wildlife Biology Program, Department of Ecosystem and Conservation Science, College of Forestry and Conservation, University of Montana, Missoula, Montana, United States of America
| | - John Bardsley
- Department of Mathematics and Statistics, University of Montana, Missoula, Montana, United States of America
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31
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Cosner C, Winkler M. Well-posedness and qualitative properties of a dynamical model for the ideal free distribution. J Math Biol 2013; 69:1343-82. [PMID: 24170293 DOI: 10.1007/s00285-013-0733-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 09/29/2013] [Indexed: 10/26/2022]
Abstract
Understanding the spatial distribution of populations in heterogeneous environments is an important problem in ecology. In the case of a population of organisms that can sense the quality of their environment and move to increase their fitness, one theoretical description of the expected distribution of the population is the ideal free distribution, where individuals locate themselves to optimize fitness. A model for a dynamical process that allows a population to achieve an ideal free distribution was proposed by the Cosner (Theor Popul Biol 67:101-108, 2005). The model is based on a reaction-diffusion-advection equation with nonlinear diffusion which is similar to a porous medium equation with additional advection and population growth terms. We establish that the model is well-posed, show that solutions stabilize, determine the stationary states, discuss their stability, and describe the biological interpretation of the results.
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Affiliation(s)
- Chris Cosner
- Department of Mathematics, University of Miami Coral Gables, Florida, USA,
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32
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Williams AC, Flaherty SE, Flaxman SM. Quantitative tests of multitrophic ideal free distribution theory. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.06.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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33
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Pauwels I, Mouton A, Baetens J, Van Nieuland S, De Baets B, Goethals P. Modelling a pike (Esox lucius) population in a lowland river using a cellular automaton. ECOL INFORM 2013. [DOI: 10.1016/j.ecoinf.2012.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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34
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van Beest FM, Uzal A, Vander Wal E, Laforge MP, Contasti AL, Colville D, McLoughlin PD. Increasing density leads to generalization in both coarse-grained habitat selection and fine-grained resource selection in a large mammal. J Anim Ecol 2013; 83:147-56. [DOI: 10.1111/1365-2656.12115] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 06/15/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Floris M. van Beest
- Department of Animal and Poultry Science; College of Agriculture and Bioresources; University of Saskatchewan; 51 Campus Drive Saskatoon SK S7N 5E2 Canada
| | - Antonio Uzal
- Department of Biology; University of Saskatchewan; 112 Science Place Saskatoon SK S7N 5E2 Canada
| | - Eric Vander Wal
- Département de biologie; Université de Sherbooke; 2500 boul. de l'université Sherbrooke QC J1K 2R1 Canada
| | - Michel P. Laforge
- Department of Biology; University of Saskatchewan; 112 Science Place Saskatoon SK S7N 5E2 Canada
| | - Adrienne L. Contasti
- Department of Biology; University of Saskatchewan; 112 Science Place Saskatoon SK S7N 5E2 Canada
| | - David Colville
- Applied Geomatics Research Group; Centre of Geographic Sciences; Nova Scotia Community College; Middleton NS B0S 1P0 Canada
| | - Philip D. McLoughlin
- Department of Biology; University of Saskatchewan; 112 Science Place Saskatoon SK S7N 5E2 Canada
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Haché S, Villard MA, Bayne EM. Experimental evidence for an ideal free distribution in a breeding population of a territorial songbird. Ecology 2013. [DOI: 10.1890/12-1025.1] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Jonzén N. Habitat Selection: Implications for Monitoring, Management, and Conservation. Isr J Ecol Evol 2013. [DOI: 10.1560/ijee.54.3-4.459] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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van der Hammen T, Montserrat M, Sabelis MW, de Roos AM, Janssen A. Whether ideal free or not, predatory mites distribute so as to maximize reproduction. Oecologia 2012; 169:95-104. [PMID: 22081260 PMCID: PMC3326238 DOI: 10.1007/s00442-011-2190-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 10/17/2011] [Indexed: 12/02/2022]
Abstract
Ideal free distribution (IFD) models predict that animals distribute themselves such that no individual can increase its fitness by moving to another patch. Many empirical tests assume that the interference among animals is independent of density and do not quantify the effects of density on fitness traits. Using two species of predatory mites, we measured oviposition as a function of conspecific density. Subsequently, we used these functions to calculate expected distributions on two connected patches. We performed an experimental test of the distributions of mites on two such connected patches, among which one had a food accessibility rate that was twice as high as on the other. For one of the two species, Iphiseius degenerans, the distribution matched the expected distribution. The distribution also coincided with the ratio of food accessibility. The other species, Neoseiulus cucumeris, distributed itself differently than expected. However, the oviposition rates of both species did not differ significantly from the expected oviposition rates based on experiments on single patches. This suggests that the oviposition rate of N. cucumeris was not negatively affected by the observed distribution, despite the fact that N. cucumeris did not match the predicted distributions. Thus, the distribution of one mite species, I. degenerans, was in agreement with IFD theory, whereas for the other mite species, N. cucumeris, unknown factors may have influenced the distribution of the mites. We conclude that density-dependent fitness traits provide essential information for explaining animal distributions.
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Nicolai CA, Sedinger JS. Are there trade-offs between pre- and post-fledging survival in black brent geese? J Anim Ecol 2012; 81:788-97. [PMID: 22304760 DOI: 10.1111/j.1365-2656.2012.01952.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
1. The growth period is an important determinant of fitness later in life through its effects on first-year survival and future reproduction. Choices by adult females about where to rear their offspring strongly affect growth rates and offspring fitness in geese. 2. Individual female black brent (Branta bernicla nigricans) tend to raise their broods in the same areas each year, and these areas are consistently ranked with respect to growth rates of goslings. Therefore, some females consistently rear their broods on areas resulting in lower post-fledging fitness. 3. We explore the potential that growth rates of offspring (and associated fitness consequences) are traded off against other vital rates influencing fitness of either adult females or goslings. Growth of goslings primarily influences fitness after fledging, so one hypothesis is that survival before fledging, which is influenced by predation, is traded off against growth rates and post-fledging survival. 4. We estimated pre-fledging and post-fledging survival for goslings reared on areas used by broods from the Tutakoke River black brent colony. We examined recaptures, recoveries by hunters and resightings of brent marked as goslings with webtags and standard leg rings. These data were analyzed using capture-mark-recapture models in program mark to derive separate estimates of pre- and post-fledging survival for 18 cohorts (1987-2004) of black brent goslings across seven brood rearing areas (BRAs). 5. Estimates of pre-fledging survival probability varied from 0·00 ± 0·00 (mean ± 95% confidence interval) to 0·92 ± 0·1; and estimates of post-fledging survival probability varied from 0·00 ± 0·00 to 1·00 ± 0·08. Substantial variation existed both among BRAs and years but post-fledging survival declined substantially during the study. 6. Pre- and post-fledging survival were positively correlated, exhibiting a quadratic relationship (ß(post-fledging survival) = 1·00 (±0·47)x-0·83 (±0·480)x(2) , where x = pre-fledging survival). Therefore, we did not find a trade-off between pre- and post-fledging survival in black brent goslings across BRAs, suggesting that factors other than foraging conditions and predation on goslings must influence selection of BRAs.
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Affiliation(s)
- Christopher A Nicolai
- Department of Natural Resources and Environmental Science, University of Nevada Reno, Reno, NV 89512, USA.
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39
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Hammond CAM, Mitchell MS, Bissell GN. Territory occupancy by common loons in response to disturbance, habitat, and intraspecific relationships. J Wildl Manage 2011. [DOI: 10.1002/jwmg.298] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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40
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Acolas ML, Labonne J, Baglinière JL, Roussel JM. The role of body size versus growth on the decision to migrate: a case study with Salmo trutta. Naturwissenschaften 2011; 99:11-21. [DOI: 10.1007/s00114-011-0861-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/20/2011] [Accepted: 10/22/2011] [Indexed: 11/30/2022]
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Quaintenne G, van Gils JA, Bocher P, Dekinga A, Piersma T. Scaling up ideals to freedom: are densities of red knots across western Europe consistent with ideal free distribution? Proc Biol Sci 2011; 278:2728-36. [PMID: 21325322 PMCID: PMC3145193 DOI: 10.1098/rspb.2011.0026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Accepted: 01/27/2011] [Indexed: 11/12/2022] Open
Abstract
Local studies have shown that the distribution of red knots Calidris canutus across intertidal mudflats is consistent with the predictions of an ideal distribution, but not a free distribution. Here, we scale up the study of feeding distributions to their entire wintering area in western Europe. Densities of red knots were compared among seven wintering sites in The Netherlands, UK and France, where the available mollusc food stocks were also measured and from where diets were known. We tested between three different distribution models that respectively assumed (i) a uniform distribution of red knots over all areas, (ii) a uniform distribution across all suitable habitat (based on threshold densities of harvestable mollusc prey), and (iii) an ideal and free distribution (IFD) across all suitable habitats. Red knots were not homogeneously distributed across the different European wintering areas, also not when considering suitable habitats only. Their distribution was best explained by the IFD model, suggesting that the birds are exposed to interference and have good knowledge about their resource landscape at the spatial scale of NW Europe, and that the costs of movement between estuaries, at least when averaged over a whole winter, are negligible.
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Affiliation(s)
- Gwenaël Quaintenne
- Laboratory Littoral Environnement et Sociétés, UMR6250, CNRS-ULR, University of La Rochelle, 17000 La Rochelle, France.
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Kausrud KL, Grégoire JC, Skarpaas O, Erbilgin N, Gilbert M, Økland B, Stenseth NC. Trees wanted--dead or alive! Host selection and population dynamics in tree-killing bark beetles. PLoS One 2011; 6:e18274. [PMID: 21647433 PMCID: PMC3102062 DOI: 10.1371/journal.pone.0018274] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/25/2011] [Indexed: 11/18/2022] Open
Abstract
Bark beetles (Coleoptera: Curculionidae, Scolytinae) feed and breed in dead or severely weakened host trees. When their population densities are high, some species aggregate on healthy host trees so that their defences may be exhausted and the inner bark successfully colonized, killing the tree in the process. Here we investigate under what conditions participating with unrelated conspecifics in risky mass attacks on living trees is an adaptive strategy, and what this can tell us about bark beetle outbreak dynamics. We find that the outcome of individual host selection may deviate from the ideal free distribution in a way that facilitates the emergence of tree-killing (aggressive) behavior, and that any heritability on traits governing aggressiveness seems likely to exist in a state of flux or cycles consistent with variability observed in natural populations. This may have implications for how economically and ecologically important species respond to environmental changes in climate and landscape (forest) structure. The population dynamics emerging from individual behavior are complex, capable of switching between "endemic" and "epidemic" regimes spontaneously or following changes in host availability or resistance. Model predictions are compared to empirical observations, and we identify some factors determining the occurrence and self-limitation of epidemics.
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Affiliation(s)
- Kyrre L. Kausrud
- Department of Biology, Centre for Ecological
and Evolutionary Synthesis (CEES), University of Oslo, Oslo, Norway
- Norwegian Forest and Landscape Institute,
Ås, Norway
| | - Jean-Claude Grégoire
- Lutte Biologique et Ecologie Spatiale,
Université Libre de Bruxelles, Bruxelles, Belgium
| | - Olav Skarpaas
- The Norwegian Institute for Nature Research,
Oslo, Norway
| | - Nadir Erbilgin
- Department of Renewable Resources, University
of Alberta, Edmonton, Alberta, Canada
| | - Marius Gilbert
- Biological Control and Spatial Ecology,
Université Libre de Bruxelles, Brussels, Belgium
- Fonds National de la Recherche Scientifique,
Brussels, Belgium
| | - Bjørn Økland
- Norwegian Forest and Landscape Institute,
Ås, Norway
| | - Nils Chr. Stenseth
- Department of Biology, Centre for Ecological
and Evolutionary Synthesis (CEES), University of Oslo, Oslo, Norway
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Morris DW, MacEachern JT. Active density-dependent habitat selection in a controlled population of small mammals. Ecology 2010; 91:3131-7. [PMID: 21141174 DOI: 10.1890/10-0479.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Density-dependent habitat selection has numerous and far-reaching implications to population dynamics and evolutionary processes. Although several studies suggest that organisms choose and occupy high-quality habitats over poorer ones, definitive experiments demonstrating active selection, by the same individuals at the appropriate population scale, are lacking. We conducted a reciprocal food supplementation experiment to assess whether voles would first occupy a habitat receiving extra food, then change their preference to track food supplements moved to another habitat. Meadow voles, as predicted, were more abundant in food-supplemented habitat than in others. Density declined when food supplements ceased because the voles moved to the new habitat receiving extra food. Although males and females appeared to follow different strategies, meadow-vole densities reflected habitat quality because voles actively selected the best habitat available. It is thus clear that behavioral decisions on habitat use can motivate patterns of abundance, frequency, and gene flow that have widespread effects on subsequent evolution.
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Affiliation(s)
- Douglas W Morris
- Department of Biology, Lakehead University, Thunder Bay, Ontario P7B 5E1, Canada.
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Gaillard JM, Hebblewhite M, Loison A, Fuller M, Powell R, Basille M, Van Moorter B. Habitat-performance relationships: finding the right metric at a given spatial scale. Philos Trans R Soc Lond B Biol Sci 2010; 365:2255-65. [PMID: 20566502 DOI: 10.1098/rstb.2010.0085] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The field of habitat ecology has been muddled by imprecise terminology regarding what constitutes habitat, and how importance is measured through use, selection, avoidance and other bio-statistical terminology. Added to the confusion is the idea that habitat is scale-specific. Despite these conceptual difficulties, ecologists have made advances in understanding 'how habitats are important to animals', and data from animal-borne global positioning system (GPS) units have the potential to help this clarification. Here, we propose a new conceptual framework to connect habitats with measures of animal performance itself--towards assessing habitat-performance relationship (HPR). Long-term studies will be needed to estimate consequences of habitat selection for animal performance. GPS data from wildlife can provide new approaches for studying useful correlates of performance that we review. Recent examples include merging traditional resource selection studies with information about resources used at different critical life-history events (e.g. nesting, calving, migration), uncovering habitats that facilitate movement or foraging and, ultimately, comparing resources used through different life-history strategies with those resulting in death. By integrating data from GPS receivers with other animal-borne technologies and combining those data with additional life-history information, we believe understanding the drivers of HPRs will inform animal ecology and improve conservation.
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Affiliation(s)
- Jean-Michel Gaillard
- Unité Mixte de Recherche CNRS-Université Lyon 1 N degrees 5558 Biométrie et Biologie Evolutive, Bâtiment Gregor Mendel, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
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Matsumura S, Arlinghaus R, Dieckmann U. Foraging on spatially distributed resources with sub-optimal movement, imperfect information, and travelling costs: departures from the ideal free distribution. OIKOS 2010. [DOI: 10.1111/j.1600-0706.2010.18196.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hodson J, Fortin D, Leblanc ML, Bélanger L. An appraisal of the fitness consequences of forest disturbance for wildlife using habitat selection theory. Oecologia 2010; 164:73-86. [PMID: 20658153 DOI: 10.1007/s00442-010-1691-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2009] [Accepted: 06/07/2010] [Indexed: 11/25/2022]
Abstract
Isodar theory can help to unveil the fitness consequences of habitat disturbance for wildlife through an evaluation of adaptive habitat selection using patterns of animal abundance in adjacent habitats. By incorporating measures of disturbance intensity or variations in resource availability into fitness-density functions, we can evaluate the functional form of isodars expected under different disturbance-fitness relationships. Using this framework, we investigated how a gradient of forest harvesting disturbance and differences in resource availability influenced habitat quality for snowshoe hares (Lepus americanus) and red-backed voles (Myodes gapperi) using pairs of logged and uncut boreal forest. Isodars for both species had positive intercepts, indicating reductions to maximum potential fitness in logged stands. Habitat selection by hares depended on both conspecific density and differences in canopy cover between harvested and uncut stands. Fitness-density curves for hares in logged stands were predicted to shift from diverging to converging with those in uncut forest across a gradient of high to low disturbance intensity. Selection for uncut forests thus became less pronounced with increasing population size at low levels of logging disturbance. Voles responded to differences in moss cover between habitats which reflected moisture availability. Lower moss cover in harvested stands either reduced maximum potential fitness or increased the relative rate of decline in fitness with density. Differences in vole densities between harvested and uncut stands were predicted, however, to diminish as populations increased. Our findings underscore the importance of accounting for density-dependent behaviors when evaluating how changing habitat conditions influence animal distribution.
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Affiliation(s)
- James Hodson
- Département de Biologie, Université Laval, Ste-Foy, Québec, G1V 0A6, Canada.
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47
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Foldvik A, Finstad AG, Einum S. Relating juvenile spatial distribution to breeding patterns in anadromous salmonid populations. J Anim Ecol 2010; 79:501-9. [DOI: 10.1111/j.1365-2656.2009.01652.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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48
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Bonebrake TC, Beissinger SR. Predation and infanticide influence ideal free choice by a parrot occupying heterogeneous tropical habitats. Oecologia 2010; 163:385-93. [PMID: 20135326 PMCID: PMC2871107 DOI: 10.1007/s00442-010-1566-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 01/11/2010] [Indexed: 10/27/2022]
Abstract
The ideal free distribution (IFD) predicts that organisms will disperse to sites that maximize their fitness based on availability of resources. Habitat heterogeneity underlies resource variation and influences spatial variation in demography and the distribution of populations. We relate nest site productivity at multiple scales measured over a decade to habitat quality in a box-nesting population of Forpus passerinus (green-rumped parrotlets) in Venezuela to examine critical IFD assumptions. Variation in reproductive success at the local population and neighborhood scales had a much larger influence on productivity (fledglings per nest box per year) than nest site or female identity. Habitat features were reliable cues of nest site quality. Nest sites with less vegetative cover produced greater numbers of fledglings than sites with more cover. However, there was also a competitive cost to nesting in high-quality, low-vegetative cover nest boxes, as these sites experienced the most infanticide events. In the lowland local population, water depth and cover surrounding nest sites were related with F. passerinus productivity. Low vegetative cover and deeper water were associated with lower predation rates, suggesting that predation could be a primary factor driving habitat selection patterns. Parrotlets also demonstrated directional dispersal. Pairs that changed nest sites were more likely to disperse from poor-quality nest sites to high-quality nest sites rather than vice versa, and juveniles were more likely to disperse to, or remain in, the more productive of the two local populations. Parrotlets exhibited three characteristics fundamental to the IFD: habitat heterogeneity within and between local populations, reliable habitat cues to productivity, and active dispersal to sites of higher fitness.
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Affiliation(s)
- Timothy C Bonebrake
- Ecosystem Sciences Division, Department of Environmental Science, Policy, and Management, University of California, 37 Mulford Hall, Berkeley, CA 94720-3114, USA.
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Edeline E, Haugen TO, Weltzien FA, Claessen D, Winfield IJ, Stenseth NC, Vøllestad LA. Body downsizing caused by non-consumptive social stress severely depresses population growth rate. Proc Biol Sci 2009; 277:843-51. [PMID: 19923130 DOI: 10.1098/rspb.2009.1724] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Chronic social stress diverts energy away from growth, reproduction and immunity, and is thus a potential driver of population dynamics. However, the effects of social stress on demographic density dependence remain largely overlooked in ecological theory. Here we combine behavioural experiments, physiology and population modelling to show in a top predator (pike Esox lucius) that social stress alone may be a primary driver of demographic density dependence. Doubling pike density in experimental ponds under controlled prey availability did not significantly change prey intake by pike (i.e. did not significantly change interference or exploitative competition), but induced a neuroendocrine stress response reflecting a size-dependent dominance hierarchy, depressed pike energetic status and lowered pike body growth rate by 23 per cent. Assuming fixed size-dependent survival and fecundity functions parameterized for the Windermere (UK) pike population, stress-induced smaller body size shifts age-specific survival rates and lowers age-specific fecundity, which in Leslie matrices projects into reduced population rate of increase (lambda) by 37-56%. Our models also predict that social stress flattens elasticity profiles of lambda to age-specific survival and fecundity, thus making population persistence more dependent on old individuals. Our results suggest that accounting for non-consumptive social stress from competitors and predators is necessary to accurately understand, predict and manage food-web dynamics.
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Affiliation(s)
- Eric Edeline
- UPMC-Paris 6, UMR (CNRS) 7618, Laboratoire Biogéochimie et Ecologie des Milieux Continentaux, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris cedex 05, France.
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50
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Edeline E, Le Rouzic A, Winfield IJ, Fletcher JM, James JB, Stenseth NC, Vøllestad LA. Harvest-induced disruptive selection increases variance in fitness-related traits. Proc Biol Sci 2009; 276:4163-71. [PMID: 19740875 DOI: 10.1098/rspb.2009.1106] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The form of Darwinian selection has important ecological and management implications. Negative effects of harvesting are often ascribed to size truncation (i.e. strictly directional selection against large individuals) and resultant decrease in trait variability, which depresses capacity to buffer environmental change, hinders evolutionary rebound and ultimately impairs population recovery. However, the exact form of harvest-induced selection is generally unknown and the effects of harvest on trait variability remain unexplored. Here we use unique data from the Windermere (UK) long-term ecological experiment to show in a top predator (pike, Esox lucius) that the fishery does not induce size truncation but disruptive (diversifying) selection, and does not decrease but rather increases variability in pike somatic growth rate and size at age. This result is supported by complementary modelling approaches removing the effects of catch selectivity, selection prior to the catch and environmental variation. Therefore, fishing most likely increased genetic variability for somatic growth in pike and presumably favoured an observed rapid evolutionary rebound after fishery relaxation. Inference about the mechanisms through which harvesting negatively affects population numbers and recovery should systematically be based on a measure of the exact form of selection. From a management perspective, disruptive harvesting necessitates combining a preservation of large individuals with moderate exploitation rates, and thus provides a comprehensive tool for sustainable exploitation of natural resources.
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Affiliation(s)
- Eric Edeline
- UPMC-Paris6, UMR (CNRS) 7618, Laboratoire Biogéochimie et Ecologie des Milieux Continentaux, 46 rue d'Ulm, F-75230 Paris Cedex 05, France.
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