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Layton-Matthews K, Vriend SJG, Grøtan V, Loonen MJJE, Sæther BE, Fuglei E, Hansen BB. Extreme events, trophic chain reactions, and shifts in phenotypic selection. Sci Rep 2023; 13:15181. [PMID: 37704641 PMCID: PMC10499831 DOI: 10.1038/s41598-023-41940-6] [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: 04/03/2023] [Accepted: 09/04/2023] [Indexed: 09/15/2023] Open
Abstract
Demographic consequences of rapid environmental change and extreme climatic events (ECEs) can cascade across trophic levels with evolutionary implications that have rarely been explored. Here, we show how an ECE in high Arctic Svalbard triggered a trophic chain reaction, directly or indirectly affecting the demography of both overwintering and migratory vertebrates, ultimately inducing a shift in density-dependent phenotypic selection in migratory geese. A record-breaking rain-on-snow event and ice-locked pastures led to reindeer mass starvation and a population crash, followed by a period of low mortality and population recovery. This caused lagged, long-lasting reductions in reindeer carrion numbers and resultant low abundances of Arctic foxes, a scavenger on reindeer and predator of migratory birds. The associated decrease in Arctic fox predation of goose offspring allowed for a rapid increase in barnacle goose densities. As expected according to r- and K-selection theory, the goose body condition (affecting reproduction and post-fledging survival) maximising Malthusian fitness increased with this shift in population density. Thus, the winter ECE acting on reindeer and their scavenger, the Arctic fox, indirectly selected for higher body condition in migratory geese. This high Arctic study provides rare empirical evidence of links between ECEs, community dynamics and evolution, with implications for our understanding of indirect eco-evolutionary impacts of global change.
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Affiliation(s)
- Kate Layton-Matthews
- Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway.
- Norwegian Institute for Nature Research, NINA, Tromsø, Norway.
| | - Stefan J G Vriend
- Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Vidar Grøtan
- Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
| | | | - Bernt-Erik Sæther
- Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
| | - Eva Fuglei
- Norwegian Polar Institute, Tromsø, Norway
| | - Brage Bremset Hansen
- Department of Biology, Centre for Biodiversity Dynamics, NTNU, Trondheim, Norway
- Department of Terrestrial Ecology, Norwegian Institute for Nature Research, NINA, Trondheim, Norway
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2
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Mutshinda CM, Mishra A, Finkel ZV, Irwin AJ. Density regulation amplifies environmentally induced population fluctuations. PeerJ 2023; 11:e14701. [PMID: 36751641 PMCID: PMC9899430 DOI: 10.7717/peerj.14701] [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: 12/22/2021] [Accepted: 12/14/2022] [Indexed: 02/05/2023] Open
Abstract
Background Density-dependent regulation is ubiquitous in population dynamics, and its potential interaction with environmental stochasticity complicates the characterization of the random component of population dynamics. Yet, this issue has not received attention commensurate with its relevance for descriptive and predictive modeling of population dynamics. Here we use a Bayesian modeling approach to investigate the contribution of density regulation to population variability in stochastic environments. Methods We analytically derive a formula linking the stationary variance of population abundance/density under Gompertz regulation in a stochastic environment with constant variance to the environmental variance and the strength of density feedback, to investigate whether and how density regulation affects the stationary variance. We examine through simulations whether the relationship between stationary variance and density regulation inferred analytically under the Gompertz model carries over to the Ricker model, widely used in population dynamics modeling. Results The analytical decomposition of the stationary variance under stochastic Gompertz dynamics implies higher variability for strongly regulated populations. Simulation results demonstrate that the pattern of increasing population variability with increasing density feedback found under the Gompertz model holds for the Ricker model as well, and is expected to be a general phenomenon with stochastic population models. We also analytically established and empirically validated that the square of the autoregressive parameter of the Gompertz model in AR(1) form represents the proportion of stationary variance due to density dependence. Discussion Our results suggest that neither environmental stochasticity nor density regulation can alone explain the patterns of population variability in stochastic environments, as these two components of temporal variation interact, with a tendency for density regulation to amplify the magnitude of environmentally induced population fluctuations. This finding has far-reaching implications for population viability. It implies that intense intra-specific resource competition increases the risk of environment-driven population collapse at high density, making opportune harvesting a sensible practice for improving the resistance of managed populations such as fish stocks to environmental perturbations. The separation of density-dependent and density-independent processes will help improve population dynamics modeling, while providing a basis for evaluating the relative importance of these two categories of processes that remains a topic of long-standing controversy among ecologists.
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Affiliation(s)
- Crispin M Mutshinda
- Department of Mathematics & Statistics, Dalhousie University, Halifax, NS, Canada
| | | | - Zoe V Finkel
- Department of Oceanography, Dalhousie University, Halifax, NS, Canada
| | - Andrew J Irwin
- Department of Mathematics & Statistics, Dalhousie University, Halifax, NS, Canada
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3
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Furuichi S, Kamimura Y, Suzuki M, Yukami R. Density-dependent attributes of schooling in small pelagic fishes. Naturwissenschaften 2022; 109:49. [DOI: 10.1007/s00114-022-01819-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 09/05/2022] [Accepted: 09/07/2022] [Indexed: 10/14/2022]
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4
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Sandal L, Grøtan V, Saether BE, Freckleton RP, Noble DG, Ovaskainen O. Effects of density, species interactions, and environmental stochasticity on the dynamics of British bird communities. Ecology 2022; 103:e3731. [PMID: 35416286 PMCID: PMC9539587 DOI: 10.1002/ecy.3731] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/13/2021] [Accepted: 02/16/2022] [Indexed: 12/03/2022]
Abstract
Our knowledge of the factors affecting species abundances is mainly based on time‐series analyses of a few well‐studied species at single or few localities, but we know little about whether results from such analyses can be extrapolated to the community level. We apply a joint species distribution model to long‐term time‐series data on British bird communities to examine the relative contribution of intra‐ and interspecific density dependence at different spatial scales, as well as the influence of environmental stochasticity, to spatiotemporal interspecific variation in abundance. Intraspecific density dependence has the major structuring effect on these bird communities. In addition, environmental fluctuations affect spatiotemporal differences in abundance. In contrast, species interactions had a minor impact on variation in abundance. Thus, important drivers of single‐species dynamics are also strongly affecting dynamics of communities in time and space.
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Affiliation(s)
- Lisa Sandal
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, Trondheim, Norway
| | - Vidar Grøtan
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, Trondheim, Norway
| | - Bernt-Erik Saether
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, Trondheim, Norway
| | - Robert P Freckleton
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield, UK
| | | | - Otso Ovaskainen
- Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, Trondheim, Norway.,Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35 (Survontie 9C), Jyväskylä, Finland.,Organismal and Evolutionary Biology Research Program, University of Helsinki, Helsinki, Finland
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5
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Sørbye SH, Nicolau PG, Rue H. Finite-sample properties of estimators for first and second order autoregressive processes. STATISTICAL INFERENCE FOR STOCHASTIC PROCESSES 2021. [DOI: 10.1007/s11203-021-09262-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractThe class of autoregressive (AR) processes is extensively used to model temporal dependence in observed time series. Such models are easily available and routinely fitted using freely available statistical software like . A potential problem is that commonly applied estimators for the coefficients of AR processes are severely biased when the time series are short. This paper studies the finite-sample properties of well-known estimators for the coefficients of stationary AR(1) and AR(2) processes and provides bias-corrected versions of these estimators which are quick and easy to apply. The new estimators are constructed by modeling the relationship between the true and originally estimated AR coefficients using weighted orthogonal polynomial regression, taking the sampling distribution of the original estimators into account. The finite-sample distributions of the new bias-corrected estimators are approximated using transformations of skew-normal densities, combined with a Gaussian copula approximation in the AR(2) case. The properties of the new estimators are demonstrated by simulations and in the analysis of a real ecological data set. The estimators are easily available in our accompanying -package for AR(1) and AR(2) processes of length 10–50, both giving bias-corrected coefficient estimates and corresponding confidence intervals.
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6
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Frafjord K. Population dynamics of an island population of water voles Arvicola amphibius (Linnaeus, 1758) with one major predator, the eagle owl Bubo bubo (Linnaeus, 1758), in northern Norway. Polar Biol 2021. [DOI: 10.1007/s00300-021-02964-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractPredator–prey relationships are of great significance to ecosystems, and their effects on the population dynamics of voles and lemmings (Microtinae) in Boreal and Arctic environments have long been of particular interest. A simple ecosystem with one major prey and one major predator could be an ideal setting for a study of their interactions. This is the situation on several small islands on the coast of northern Norway just below the Arctic Circle, with populations of water voles Arvicola amphibius preyed upon by the eagle owl Bubo bubo. The population dynamics of the water vole was studied by trapping and tagging in 2003–2018, eagle owl pellets were collected for analyses, eagle owl breeding attempts were recorded, and some weather variables collected from official recordings. After having been introduced well into the study period, the number of sheep Ovis aries was also recorded. Water voles were the main prey of the eagle owl, with 89% occurrence in pellets, with an overrepresentation of adults and males. Both predation, sheep grazing and extreme weather events influenced the vole population. Predator exclusion, as happened in three summers due to an intensive radio tracking study, especially increased the number of surviving young (in particular from the early cohorts) and the mass of adults. Extreme weather events, such as flooding in summer and deeply frozen ground in winter, most significantly reduced vole populations. Sheep grazing may exacerbate the effects of predation. A similar multitude of factors may affect populations of other rodent species as well.
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7
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Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem. Proc Natl Acad Sci U S A 2021; 118:2106635118. [PMID: 34504000 PMCID: PMC8449336 DOI: 10.1073/pnas.2106635118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2021] [Indexed: 11/18/2022] Open
Abstract
Whether the renowned population cycles of small mammals in northern food webs are driven by bottom-up (plant–herbivore) or top-down (predator–prey) interactions is still a debated question but crucial to our understanding of their ecological functions and response to climate change. A long-term study of a graminivorous vole population in an exceptionally simple High Arctic food web allowed us to identify which population dynamics features are present without top-down regulation. Unique features were high-amplitude, noncyclic population fluctuations driven by a combination of stochastic weather events and season-specific density dependence likely arising from plant–herbivore interactions. That such features are not present in more complex food webs points to the importance of top-down regulation in small mammal populations. Ecologists are still puzzled by the diverse population dynamics of herbivorous small mammals that range from high-amplitude, multiannual cycles to stable dynamics. Theory predicts that this diversity results from combinations of climatic seasonality, weather stochasticity, and density-dependent food web interactions. The almost ubiquitous 3- to 5-y cycles in boreal and arctic climates may theoretically result from bottom-up (plant–herbivore) and top-down (predator–prey) interactions. Assessing, empirically, the roles of such interactions and how they are influenced by environmental stochasticity has been hampered by food web complexity. Here, we take advantage of a uniquely simple High Arctic food web, which allowed us to analyze the dynamics of a graminivorous vole population not subjected to top-down regulation. This population exhibited high-amplitude, noncyclic fluctuations—partly driven by weather stochasticity. However, the predominant driver of the dynamics was overcompensatory density dependence in winter that caused the population to frequently crash. Model simulations showed that the seasonal pattern of density dependence would yield regular 2-y cycles in the absence of stochasticity. While such short cycles have not yet been observed in mammals, they are theoretically plausible if graminivorous vole populations are deterministically bottom-up regulated. When incorporating weather stochasticity in the model simulations, cyclicity became disrupted and the amplitude was increased—akin to the observed dynamics. Our findings contrast with the 3- to 5-y population cycles that are typical of graminivorous small mammals in more complex food webs, suggesting that top-down regulation is normally an important component of such dynamics.
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Evolutionary Relationships of Ljungan Virus Variants Circulating in Multi-Host Systems across Europe. Viruses 2021; 13:v13071317. [PMID: 34372523 PMCID: PMC8310206 DOI: 10.3390/v13071317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/01/2021] [Accepted: 07/02/2021] [Indexed: 12/12/2022] Open
Abstract
The picornavirus named 'Ljungan virus' (LV, species Parechovirus B) has been detected in a dozen small mammal species from across Europe, but detailed information on its genetic diversity and host specificity is lacking. Here, we analyze the evolutionary relationships of LV variants circulating in free-living mammal populations by comparing the phylogenetics of the VP1 region (encoding the capsid protein and associated with LV serotype) and the 3Dpol region (encoding the RNA polymerase) from 24 LV RNA-positive animals and a fragment of the 5' untranslated region (UTR) sequence (used for defining strains) in sympatric small mammals. We define three new VP1 genotypes: two in bank voles (Myodes glareolus) (genotype 8 from Finland, Sweden, France, and Italy, and genotype 9 from France and Italy) and one in field voles (Microtus arvalis) (genotype 7 from Finland). There are several other indications that LV variants are host-specific, at least in parts of their range. Our results suggest that LV evolution is rapid, ongoing and affected by genetic drift, purifying selection, spillover and host evolutionary history. Although recent studies suggest that LV does not have zoonotic potential, its widespread geographical and host distribution in natural populations of well-characterized small mammals could make it useful as a model for studying RNA virus evolution and transmission.
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9
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Lemoine NP. Unifying ecosystem responses to disturbance into a single statistical framework. OIKOS 2020. [DOI: 10.1111/oik.07752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Nathan P. Lemoine
- Dept of Biological Sciences, Marquette Univ. Milwaukee WI USA
- Dept of Zoology, Milwaukee Public Museum Milwaukee WI USA
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10
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Abstract
Demonstrating asymmetric competition in natural systems is difficult, as the effect of large individuals on small ones has to be measured, and vice versa. Numerous experiments have quantified one side of the interaction, typically the effect of large individuals on small ones. Here, we demonstrate, using a long-term study of guppies, that an individual’s performance depends on its relative size, with large individuals being competitively dominant. Accurate prediction of both the mean and variance in body size was possible by using models incorporating asymmetric competition, whereas in models where individuals are competitively equivalent, the predictions were poor. Biotic interactions are central to both ecological and evolutionary dynamics. In the vast majority of empirical studies, the strength of intraspecific interactions is estimated by using simple measures of population size. Biologists have long known that these are crude metrics, with experiments and theory suggesting that interactions between individuals should depend on traits, such as body size. Despite this, it has been difficult to estimate the impact of traits on competitive ability from ecological field data, and this explains why the strength of biotic interactions has empirically been treated in a simplistic manner. Using long-term observational data from four different populations, we show that large Trinidadian guppies impose a significantly larger competitive pressure on conspecifics than individuals that are smaller; in other words, competition is asymmetric. When we incorporate this asymmetry into integral projection models, the predicted size structure is much closer to what we see in the field compared with models where competition is independent of body size. This difference in size structure translates into a twofold difference in reproductive output. This demonstrates how the nature of ecological interactions drives the size structure, which, in turn, will have important implications for both the ecological and evolutionary dynamics.
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11
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Andreassen HP, Johnsen K, Joncour B, Neby M, Odden M. Seasonality shapes the amplitude of vole population dynamics rather than generalist predators. OIKOS 2019. [DOI: 10.1111/oik.06351] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Harry P. Andreassen
- Inland Norway Univ. of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad NO‐2480 Koppang Norway
| | - Kaja Johnsen
- Inland Norway Univ. of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad NO‐2480 Koppang Norway
| | | | - Magne Neby
- Inland Norway Univ. of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad NO‐2480 Koppang Norway
| | - Morten Odden
- Inland Norway Univ. of Applied Sciences, Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Campus Evenstad NO‐2480 Koppang Norway
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12
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Li Z, Dai B. Global dynamics of delayed intraguild predation model with intraspecific competition. INT J BIOMATH 2019. [DOI: 10.1142/s1793524518501164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A delayed intraguild predation (IGP) model with intraspecific competition is considered. It is shown that the delay has a destabilizing effect and induces oscillations. The global existence results of periodic solutions bifurcating from the positive equilibrium are established. It is shown that there exists at least one nontrival periodic solution when the delay passes through a certain critical value. Numerical simulations are performed to illustrate our theoretical results and show that intraspecific competition can also affect the stability of the positive equilibrium of the system.
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Affiliation(s)
- Zhenzhen Li
- School of Mathematics and Statistics, Central South University, Changsha, Hunan 410083, P. R. China
| | - Binxiang Dai
- School of Mathematics and Statistics, Central South University, Changsha, Hunan 410083, P. R. China
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13
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Černý D, Lee K, Medal J, Blumstein DT. Applying Lanchester’s laws to the interspecific competition of coral reef fish. Behav Ecol 2018. [DOI: 10.1093/beheco/ary182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- David Černý
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
- Department of Geophysical Sciences, University of Chicago, Chicago, IL, USA
| | - Kristen Lee
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Jocelyn Medal
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Daniel T Blumstein
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
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14
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Webber QMR, Vander Wal E. An evolutionary framework outlining the integration of individual social and spatial ecology. J Anim Ecol 2017; 87:113-127. [PMID: 29055050 DOI: 10.1111/1365-2656.12773] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 10/08/2017] [Indexed: 11/29/2022]
Abstract
Behaviour is the interface between an organism and its environment, and behavioural plasticity is important for organisms to cope with environmental change. Social behaviour is particularly important because sociality is a dynamic process, where environmental variation influences group dynamics and social plasticity can mediate resource acquisition. Heterogeneity in the ecological environment can therefore influence the social environment. The combination of the ecological and social environments may be interpreted collectively as the "socioecological environment," which could explain variation in fitness. Our objective was to outline a framework through which individual social and spatial phenotypes can be integrated and interpreted as phenotypes that covary as a function of changes in the socioecological environment. We propose the socioecological environment is composed of individual behavioural traits, including sociality and habitat selection, both of which are repeatable, potentially heritable and may reflect animal personality traits. We also highlight how ecological and social niche theory can be applied to the socioecological environment framework, where individuals occupy different socioecological niches. Individual sociality and habitat selection are also density-dependent, and theory predicts that density-dependent traits should affect reproduction, survival, and therefore fitness and population dynamics. We then illustrate the proximate links between sociality, habitat selection and fitness as well as the ultimate, and possibly adaptive, consequences associated with changes in population density. The ecological, evolutionary and applied implications of our proposed socioecological environment framework are broad and changes in density could influence individual fitness and population dynamics. For instance, human-induced environmental changes can influence population density, which can affect the distribution of social and spatial phenotypes within a population. In summary, we outline a conceptual framework that incorporates individual social and spatial behavioural traits with fitness and we highlight a range of ecological and evolutionary processes that are likely associated with the socioecological environment.
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Affiliation(s)
- Quinn M R Webber
- Cognitive and Behavioural Ecology Interdisciplinary Program, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Eric Vander Wal
- Cognitive and Behavioural Ecology Interdisciplinary Program, Memorial University of Newfoundland, St. John's, NL, Canada.,Department of Biology, Memorial University of Newfoundland, St. John's, NL, Canada
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15
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Cerri J, Ferretti M, Bertolino S. Rabbits killing hares: an invasive mammal modifies native predator-prey dynamics. Anim Conserv 2017. [DOI: 10.1111/acv.12343] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Cerri
- Istituto di Management; Scuola Superiore Sant'Anna; Pisa Italy
| | - M. Ferretti
- Regione Toscana; Corso Gramsci; Pistoia Italy
| | - S. Bertolino
- Department of Life Sciences and Systems Biology; Torino Italy
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16
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Jankovic M, Petrovskii S, Banerjee M. Delay driven spatiotemporal chaos in single species population dynamics models. Theor Popul Biol 2016; 110:51-62. [PMID: 27154920 DOI: 10.1016/j.tpb.2016.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 04/11/2016] [Accepted: 04/26/2016] [Indexed: 11/30/2022]
Abstract
Questions surrounding the prevalence of complex population dynamics form one of the central themes in ecology. Limit cycles and spatiotemporal chaos are examples that have been widely recognised theoretically, although their importance and applicability to natural populations remains debatable. The ecological processes underlying such dynamics are thought to be numerous, though there seems to be consent as to delayed density dependence being one of the main driving forces. Indeed, time delay is a common feature of many ecological systems and can significantly influence population dynamics. In general, time delays may arise from inter- and intra-specific trophic interactions or population structure, however in the context of single species populations they are linked to more intrinsic biological phenomena such as gestation or resource regeneration. In this paper, we consider theoretically the spatiotemporal dynamics of a single species population using two different mathematical formulations. Firstly, we revisit the diffusive logistic equation in which the per capita growth is a function of some specified delayed argument. We then modify the model by incorporating a spatial convolution which results in a biologically more viable integro-differential model. Using the combination of analytical and numerical techniques, we investigate the effect of time delay on pattern formation. In particular, we show that for sufficiently large values of time delay the system's dynamics are indicative to spatiotemporal chaos. The chaotic dynamics arising in the wake of a travelling population front can be preceded by either a plateau corresponding to dynamical stabilisation of the unstable equilibrium or by periodic oscillations.
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Affiliation(s)
- Masha Jankovic
- Department of Mathematics, University of Leicester, Leicester, UK
| | | | - Malay Banerjee
- Department of Mathematics and Statistics, IIT Kanpur, India
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17
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Morozov AY, Banerjee M, Petrovskii SV. Long-term transients and complex dynamics of a stage-structured population with time delay and the Allee effect. J Theor Biol 2016; 396:116-24. [PMID: 26921467 DOI: 10.1016/j.jtbi.2016.02.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 01/27/2016] [Accepted: 02/12/2016] [Indexed: 10/22/2022]
Abstract
Traditionally, mathematical modeling in population ecology is mainly focused on asymptotic behavior of the model, i.e. as given by the system attractors. Recently, however, transient regimes and especially long-term transients have been recognized as playing a crucial role in the dynamics of ecosystems. In particular, long-term transients are a potential explanation of ecological regime shifts, when an apparently healthy population suddenly collapses and goes extinct. In this paper, we show that the interplay between delay in maturation and a strong Allee effect can result in long-term transients in a single species system. We first derive a simple 'conceptual' model of the population dynamics that incorporates both a strong Allee effect and maturation delay. Unlike much of the previous work, our approach is not empirical since our model is derived from basic principles. We show that the model exhibits a high complexity in its asymptotic dynamics including multi-periodic and chaotic attractors. We then show the existence of long-term transient dynamics in the system, when the population size oscillates for a long time between locally stable stationary states before it eventually settles either at the persistence equilibrium or goes extinct. The parametric space of the model is found to have a complex structure with the basins of attraction corresponding to the persistence and extinction states being of a complicated shape. This impedes the prediction of the eventual fate of the population, as a small variation in the maturation delay or the initial population size can either bring the population to extinction or ensure its persistence.
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Affiliation(s)
- A Yu Morozov
- Department of Mathematics, University of Leicester, LE1 7RH, UK
| | - M Banerjee
- Department of Mathematics and Statistics, Indian Institute of Technology Kanpur, Kanpur, India.
| | - S V Petrovskii
- Department of Mathematics, University of Leicester, LE1 7RH, UK
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18
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Calandra I, Zub K, Szafrańska PA, Zalewski A, Merceron G. Silicon-based plant defences, tooth wear and voles. J Exp Biol 2016; 219:501-7. [DOI: 10.1242/jeb.134890] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Plant–herbivore interactions are hypothesized to drive vole population cycles through the grazing-induced production of phytoliths in leaves. Phytoliths act as mechanical defences because they deter herbivory and lower growth rates in mammals. However, how phytoliths impair herbivore performance is still unknown. Here, we tested whether the amount of phytoliths changes tooth wear patterns. If confirmed, abrasion from phytoliths could play a role in population crashes. We applied dental microwear texture analysis (DMTA) to laboratory and wild voles. Lab voles were fed two pelleted diets with differing amounts of silicon, which produced similar dental textures. This was most probably due to the loss of food mechanical properties through pelletization and/or the small difference in silicon concentration between diets. Wild voles were trapped in Poland during spring and summer, and every year across a population cycle. In spring, voles feed on silica-rich monocotyledons, while in the summer they also include silica-depleted dicotyledons. This was reflected in the results; the amount of silica therefore leaves a traceable record in the dental microwear texture of voles. Furthermore, voles from different phases of population cycles have different microwear textures. We tentatively propose that these differences result from grazing-induced phytolith concentrations. We hypothesize that the high amount of phytoliths in response to intense grazing in peak years may result in malocclusion and other dental abnormalities, which would explain how these silicon-based plant defences help provoke population crashes. DMTA could then be used to reconstruct vole population dynamics using teeth from pellets or palaeontological material.
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Affiliation(s)
- Ivan Calandra
- GEGENAA – EA 3795, Université de Reims Champagne-Ardenne, 51100 Reims, France
| | - Karol Zub
- Mammal Research Institute, Polish Academy of Sciences, 17-230 Białowiez˙a, Poland
| | | | - Andrzej Zalewski
- Mammal Research Institute, Polish Academy of Sciences, 17-230 Białowiez˙a, Poland
| | - Gildas Merceron
- iPHEP UMR 7262, CNRS & Université de Poitiers, 86073 Poitiers, France
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19
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Ylänne H, Stark S, Tolvanen A. Vegetation shift from deciduous to evergreen dwarf shrubs in response to selective herbivory offsets carbon losses: evidence from 19 years of warming and simulated herbivory in the subarctic tundra. GLOBAL CHANGE BIOLOGY 2015; 21:3696-3711. [PMID: 25950664 DOI: 10.1111/gcb.12964] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/06/2015] [Indexed: 06/04/2023]
Abstract
Selective herbivory of palatable plant species provides a competitive advantage for unpalatable plant species, which often have slow growth rates and produce slowly decomposable litter. We hypothesized that through a shift in the vegetation community from palatable, deciduous dwarf shrubs to unpalatable, evergreen dwarf shrubs, selective herbivory may counteract the increased shrub abundance that is otherwise found in tundra ecosystems, in turn interacting with the responses of ecosystem carbon (C) stocks and CO2 balance to climatic warming. We tested this hypothesis in a 19-year field experiment with factorial treatments of warming and simulated herbivory on the dominant deciduous dwarf shrub Vaccinium myrtillus. Warming was associated with a significantly increased vegetation abundance, with the strongest effect on deciduous dwarf shrubs, resulting in greater rates of both gross ecosystem production (GEP) and ecosystem respiration (ER) as well as increased C stocks. Simulated herbivory increased the abundance of evergreen dwarf shrubs, most importantly Empetrum nigrum ssp. hermaphroditum, which led to a recent shift in the dominant vegetation from deciduous to evergreen dwarf shrubs. Simulated herbivory caused no effect on GEP and ER or the total ecosystem C stocks, indicating that the vegetation shift counteracted the herbivore-induced C loss from the system. A larger proportion of the total ecosystem C stock was found aboveground, rather than belowground, in plots treated with simulated herbivory. We conclude that by providing a competitive advantage to unpalatable plant species with slow growth rates and long life spans, selective herbivory may promote aboveground C stocks in a warming tundra ecosystem and, through this mechanism, counteract C losses that result from plant biomass consumption.
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Affiliation(s)
- Henni Ylänne
- Department of Ecology, University of Oulu, P.O. Box 3000, Oulu, FI-90014, Finland
- Arctic Centre, University of Lapland, P.O. Box 122, Rovaniemi, FI-96101, Finland
| | - Sari Stark
- Arctic Centre, University of Lapland, P.O. Box 122, Rovaniemi, FI-96101, Finland
| | - Anne Tolvanen
- Natural Resources Institute Finland (Luke), P.O. Box 413, Oulu, FI-90014, Finland
- Thule Institute, University of Oulu, P.O. Box 7300, Oulu, FI-90014, Finland
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20
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Long-term pattern of population dynamics in the field vole from central Europe: cyclic pattern with amplitude dampening. POPUL ECOL 2015. [DOI: 10.1007/s10144-015-0504-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Calandra I, Labonne G, Mathieu O, Henttonen H, Lévêque J, Milloux MJ, Renvoisé É, Montuire S, Navarro N. Isotopic partitioning by small mammals in the subnivium. Ecol Evol 2015; 5:4132-40. [PMID: 26445663 PMCID: PMC4588660 DOI: 10.1002/ece3.1653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 07/13/2015] [Accepted: 07/25/2015] [Indexed: 01/24/2023] Open
Abstract
In the Arctic, food limitation is one of the driving factors behind small mammal population fluctuations. Active throughout the year, voles and lemmings (arvicoline rodents) are central prey in arctic food webs. Snow cover, however, makes the estimation of their winter diet challenging. We analyzed the isotopic composition of ever‐growing incisors from species of voles and lemmings in northern Finland trapped in the spring and autumn. We found that resources appear to be reasonably partitioned and largely congruent with phylogeny. Our results reveal that winter resource use can be inferred from the tooth isotopic composition of rodents sampled in the spring, when trapping can be conducted, and that resources appear to be partitioned via competition under the snow.
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Affiliation(s)
- Ivan Calandra
- GEGENAA - EA 3795 Université de Reims Champagne-Ardenne Reims France
| | - Gaëlle Labonne
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Olivier Mathieu
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | | | - Jean Lévêque
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Marie-Jeanne Milloux
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Élodie Renvoisé
- Evo-Devo Lab Institute of Biotechnology University of Helsinki Helsinki Finland
| | - Sophie Montuire
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Nicolas Navarro
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
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22
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Are time delays always destabilizing? Revisiting the role of time delays and the Allee effect. THEOR ECOL-NETH 2014. [DOI: 10.1007/s12080-014-0222-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Heyman P, Vaheri A, Lundkvist Å, Avsic-Zupanc T. Hantavirus infections in Europe: from virus carriers to a major public-health problem. Expert Rev Anti Infect Ther 2014; 7:205-17. [DOI: 10.1586/14787210.7.2.205] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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24
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Breed GA, Don Bowen W, Leonard ML. Behavioral signature of intraspecific competition and density dependence in colony-breeding marine predators. Ecol Evol 2013; 3:3838-54. [PMID: 24198943 PMCID: PMC3810878 DOI: 10.1002/ece3.754] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 07/26/2013] [Accepted: 08/12/2013] [Indexed: 11/09/2022] Open
Abstract
In populations of colony-breeding marine animals, foraging around colonies can lead to intraspecific competition. This competition affects individual foraging behavior and can cause density-dependent population growth. Where behavioral data are available, it may be possible to infer the mechanism of intraspecific competition. If these mechanics are understood, they can be used to predict the population-level functional response resulting from the competition. Using satellite relocation and dive data, we studied the use of space and foraging behavior of juvenile and adult gray seals (Halichoerus grypus) from a large (over 200,000) and growing population breeding at Sable Island, Nova Scotia (44.0 oN 60.0 oW). These data were first analyzed using a behaviorally switching state-space model to infer foraging areas followed by randomization analysis of foraging region overlap of competing age classes. Patterns of habitat use and behavioral time budgets indicate that young-of-year juveniles (YOY) were likely displaced from foraging areas near (<10 km) the breeding colony by adult females. This displacement was most pronounced in the summer. Additionally, our data suggest that YOY are less capable divers than adults and this limits the habitat available to them. However, other segregating mechanisms cannot be ruled out, and we discuss several alternate hypotheses. Mark–resight data indicate juveniles born between 1998 and 2002 have much reduced survivorship compared with cohorts born in the late 1980s, while adult survivorship has remained steady. Combined with behavioral observations, our data suggest YOY are losing an intraspecific competition between adults and juveniles, resulting in the currently observed decelerating logistic population growth. Competition theory predicts that intraspecific competition resulting in a clear losing competitor should cause compensatory population regulation. This functional response produces a smooth logistic growth curve as carrying capacity is approached, and is consistent with census data collected from this population over the past 50 years. The competitive mechanism causing compensatory regulation likely stems from the capital-breeding life-history strategy employed by gray seals. This strategy decouples reproductive success from resources available around breeding colonies and prevents females from competing with each other while young are dependent.
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Affiliation(s)
- Greg A Breed
- Department of Biology, Dalhousie University 1355 Oxford Street, Halifax, Nova Scotia, B3H 4J1, Canada
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25
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Soininen EM, Ravolainen VT, Bråthen KA, Yoccoz NG, Gielly L, Ims RA. Arctic Small Rodents Have Diverse Diets and Flexible Food Selection. PLoS One 2013; 8:e68128. [PMID: 23826371 PMCID: PMC3694920 DOI: 10.1371/journal.pone.0068128] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 05/28/2013] [Indexed: 11/18/2022] Open
Abstract
The ecology of small rodent food selection is poorly understood, as mammalian herbivore food selection theory has mainly been developed by studying ungulates. Especially, the effect of food availability on food selection in natural habitats where a range of food items are available is unknown. We studied diets and selectivity of grey-sided voles (Myodes rufocanus) and tundra voles (Microtus oeconomus), key herbivores in European tundra ecosystems, using DNA metabarcoding, a novel method enabling taxonomically detailed diet studies. In order to cover the range of food availabilities present in the wild, we employed a large-scale study design for sampling data on food availability and vole diets. Both vole species had ingested a range of plant species and selected particularly forbs and grasses. Grey-sided voles also selected ericoid shrubs and tundra voles willows. Availability of a food item rarely affected its utilization directly, although seasonal changes of diets and selection suggest that these are positively correlated with availability. Moreover, diets and selectivity were affected by availability of alternative food items. These results show that the focal sub-arctic voles have diverse diets and flexible food preferences and rarely compensate low availability of a food item with increased searching effort. Diet diversity itself is likely to be an important trait and has previously been underrated owing to methodological constraints. We suggest that the roles of alternative food item availability and search time limitations for small rodent feeding ecology should be investigated. Nomenclature Annotated Checklist of the Panarctic Flora (PAF), Vascular plants. Available at: http://nhm2.uio.no/paf/, accessed 15.6.2012.
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Affiliation(s)
- Eeva M. Soininen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
- * E-mail:
| | - Virve T. Ravolainen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Kari Anne Bråthen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Nigel G. Yoccoz
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Ludovic Gielly
- Laboratoire d’ECologie Alpine, Université Joseph Fourier, Grenoble, France
| | - Rolf A. Ims
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
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26
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Cornulier T, Yoccoz NG, Bretagnolle V, Brommer JE, Butet A, Ecke F, Elston DA, Framstad E, Henttonen H, Hörnfeldt B, Huitu O, Imholt C, Ims RA, Jacob J, Jędrzejewska B, Millon A, Petty SJ, Pietiäinen H, Tkadlec E, Zub K, Lambin X. Europe-wide dampening of population cycles in keystone herbivores. Science 2013; 340:63-6. [PMID: 23559246 DOI: 10.1126/science.1228992] [Citation(s) in RCA: 185] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Suggestions of collapse in small herbivore cycles since the 1980s have raised concerns about the loss of essential ecosystem functions. Whether such phenomena are general and result from extrinsic environmental changes or from intrinsic process stochasticity is currently unknown. Using a large compilation of time series of vole abundances, we demonstrate consistent cycle amplitude dampening associated with a reduction in winter population growth, although regulatory processes responsible for cyclicity have not been lost. The underlying syndrome of change throughout Europe and grass-eating vole species suggests a common climatic driver. Increasing intervals of low-amplitude small herbivore population fluctuations are expected in the future, and these may have cascading impacts on trophic webs across ecosystems.
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Affiliation(s)
- Thomas Cornulier
- School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.
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27
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Fukaya K, Okuda T, Hori M, Yamamoto T, Nakaoka M, Noda T. Variable processes that determine population growth and an invariant mean-variance relationship of intertidal barnacles. Ecosphere 2013. [DOI: 10.1890/es12-00272.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Andreassen HP, Glorvigen P, Rémy A, Ims RA. New views on how population-intrinsic and community-extrinsic processes interact during the vole population cycles. OIKOS 2013. [DOI: 10.1111/j.1600-0706.2012.00238.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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29
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Selva N, Hobson KA, Cortés-Avizanda A, Zalewski A, Donázar JA. Mast pulses shape trophic interactions between fluctuating rodent populations in a primeval forest. PLoS One 2012; 7:e51267. [PMID: 23251475 PMCID: PMC3519590 DOI: 10.1371/journal.pone.0051267] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/30/2012] [Indexed: 11/18/2022] Open
Abstract
How different functional responses of consumers exploiting pulsed resources affect community dynamics is an ongoing question in ecology. Tree masting is a common resource pulse in terrestrial ecosystems that can drive rodent population cycles. Using stable isotope (δ13C, δ15N) analyses, we investigated the dietary response of two fluctuating rodent species, the yellow-necked mouse Apodemus flavicollis and the bank vole Myodes glareolus, to mast events in Białowieża Forest (NE Poland). Rodent hair samples were obtained non-invasively from faeces of their predators for an 11-year period that encompassed two mast events. Spectacular seed crops of deciduous trees, namely oak Quercus robur and hornbeam Carpinus betulus, occur after several intermediate years of moderate seed production, with a post-mast year characterised by a nil crop. While a Bayesian isotopic (SIAR) mixing model showed a variety of potential vegetation inputs to rodent diets, the isotopic niche of the yellow-necked mouse was strongly associated with mast of deciduous trees (>80% of diet), showing no variation among years of different seed crop. However, bank voles showed a strong functional response; in mast years the vole shifted its diet from herbs in deciduous forest (∼66% of diet) to mast (∼74%). Only in mast years did the isotopic niche of both rodent species overlap. Previous research showed that bank voles, subordinate and more generalist than mice, showed higher fluctuations in numbers in response to masting. This study provides unique data on the functional response of key pulse consumers in forest food webs, and contributes to our understanding of rodent population fluctuations and the mechanisms governing pulse–consumer interactions.
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Affiliation(s)
- Nuria Selva
- Institute of Nature Conservation, Polish Academy of Sciences, Kraków, Poland.
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30
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Connors BM, Braun DC, Peterman R, Cooper AB, Reynolds JD, Dill LM, Ruggerone GT, Krkošek M. Migration links ocean-scale competition and local ocean conditions with exposure to farmed salmon to shape wild salmon dynamics. Conserv Lett 2012. [DOI: 10.1111/j.1755-263x.2012.00244.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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31
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Gorini L, Linnell JDC, Boitani L, Hauptmann U, Odden M, Wegge P, Nilsen EB. Guild composition and habitat use of voles in 2 forest landscapes in south-eastern Norway. Integr Zool 2011; 6:299-310. [PMID: 22182322 DOI: 10.1111/j.1749-4877.2011.00258.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It is widely believed that intensive forestry has influenced small mammal population dynamics, and thereby the entire mammalian community in Fennoscandian boreal forests. The nature of these impacts on the different species is subject to debate. We live-trapped voles between 2006 and 2009 in 2 commercially harvested forests in south-eastern Norway. We investigated the variation in vole abundance among habitat types (e.g. mature forest and clear-cut) and the hypothesis that graminivorous species such as field voles (Microtus agrestis L.) benefit from clear-cuts at the expense of forest dwellers (i.e. the bank vole, Myodes glareolus Schreb.), using fine-scale descriptors of the ground vegetation. We could not find support for the hypothesis that field voles show a preference for clear-cuts, and their overall abundance was low, while bank voles were the dominant species in all habitat types, including clear-cuts in the peak and pre-peak years. We found a positive association between bank vole abundance and bilberry (Vaccinium myrtillus L.) availability rather than a specific habitat type. Low field vole density in clear-cuts might be due to variation in local productivity and ground vegetation as well as to large variation in the species temporal dynamics. The latter is particularly associated with the widespread decline of field voles in Scandinavia. Logging has the potential to negatively affect bank vole population dynamics because of the negative effect on bilberry development.
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Affiliation(s)
- Lucrezia Gorini
- Department of Animal and Human Biology, Sapienza University of Rome, Rome, Italy.
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32
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Trosvik P, Rudi K, Straetkvern KO, Jakobsen KS, Naes T, Stenseth NC. Web of ecological interactions in an experimental gut microbiota. Environ Microbiol 2011; 12:2677-87. [PMID: 20482738 DOI: 10.1111/j.1462-2920.2010.02236.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The dynamics of all ecosystems are dictated by intrinsic, density-dependent mechanisms and by density-independent environmental forcing. In spite of the importance of the gastrointestinal microbiota in health and disease, the ecology of this system remains largely unknown. Here, we take an ecological approach to gut microbial community analysis, with statistical modelling of time series data from chemostats. This approach removes effects of host forcing, allowing us to describe a network of intrinsic interactions determining the dynamic structure of an experimental gut microbiota. Surprisingly, the main colonization pattern in this simplified model system resembled that of the human infant gut, suggesting a potentially important role of density-dependent interactions in the early gut microbiota. Knowledge of ecological structures in microbial systems may provide us with a means of controlling such systems by modifying the strength and nature of interactions among microbes and between the microbes and their environment.
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Affiliation(s)
- Pål Trosvik
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, Oslo N-0316, Norway
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33
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Abstract
Population outbreaks in tundra rodents have intrigued scientists for a century as a result of their spectacular appearances and their general lessons in ecology. One outstanding question that has led to competing hypotheses is why sympatric lemmings and voles differ in regularity and shape of their outbreaks. Lemming outbreaks may be lost for decades while vole populations maintain regular population cycles. Moreover, when lemming populations eventually irrupt, they do so more steeply than the vole populations. Norwegian lemmings exhibited a large-scale outbreak synchronously with gray-sided voles in Finnmark, northern Fennoscandia, during 2006 to 2007 for the first time in two decades. Analyses of spatial variability of this outbreak across altitudinal gradients allowed us to identify determinants of the contrasting lemming and vole dynamics. The steeper lemming outbreak trajectories were caused by breeding and population growth during winter, when nonbreeding vole populations consistently declined. The differently shaped lemming and vole outbreaks appear to result from a particular demographic tactic of lemmings that evolved as an adaptation to the long and cold Arctic-Alpine winters. The lemming outbreak amplitude increased with altitude and vole density, indicating that lemming outbreaks are jointly facilitated by low temperatures and apparent mutualism with voles mediated by shared predators. High sensitivity to variation in climate and predation is likely to be the reasons why lemmings have more erratic population dynamics than sympatric voles. The combination of continued climatic warming and dampened vole cycles is expected to further decrease the frequency, amplitude, and geographic range of lemming outbreaks in tundra ecosystems.
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34
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35
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Solonen T, Ahola P. Intrinsic and extrinsic factors in the dynamics of local small-mammal populations. CAN J ZOOL 2010. [DOI: 10.1139/z09-138] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied dynamics of local small-mammal assemblages consisting of shrews, voles, and mice by small-scale snap trapping in each spring and autumn from 1981 to 2006 in southern Finland. Our aim was to search for relative roles of possible regulatory associations within and between species, as well as to find reflections of the effects of large-scale climatic phenomena on local populations. Preceding intraspecific densities had a dominating role in seasonal changes in small-mammal numbers. Their relationships with weather-related factors indicated by the indices of the North Atlantic Oscillation (NAO) were most pronounced during winter. Relationships with the NAO indices, increasing values of which indicate milder weather in the north, were negative in voles but positive in shrews and mice. Spring densities were governed by the largely compensatory effects of the growth rate of the preceding summer and subsequent population decline during winter in the field vole ( Microtus agrestis (L., 1761)) and mice, while the effects of winter decline dominated in shrews. The bank vole ( Myodes glareolus (Schreber, 1780) = Clethrionomys glareolus (Schreber, 1780)) showed decreasing winter decline, which had a considerable positive effect on population densities.
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Affiliation(s)
- T. Solonen
- Luontotutkimus Solonen Oy, Neitsytsaarentie 7b B 147, Helsinki FI-00960, Finland
- Kolsintie 12 B, Helsinki FI-00920, Finland
| | - P. Ahola
- Luontotutkimus Solonen Oy, Neitsytsaarentie 7b B 147, Helsinki FI-00960, Finland
- Kolsintie 12 B, Helsinki FI-00920, Finland
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36
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Hipkiss T, Stefansson O, Hörnfeldt B. Effect of cyclic and declining food supply on great grey owls in boreal Sweden. CAN J ZOOL 2008. [DOI: 10.1139/z08-131] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study of 35 years of data, we examine the short-term (cyclic) and long-term relationship between breeding success of great grey owls ( Strix nebulosa Forster, 1772) and their food supply (bank voles ( Clethrionomys glareolus (Schreber, 1780)), grey-sided voles ( Clethrionomys rufocanus (Sundevall, 1846)), and field voles ( Microtus agrestis (L., 1761))) in northern Sweden. Annual number of owl nests showed a 3 year cyclicity, which as predicted, corresponded to the length of the vole cycle in the region. Mean annual brood size also fluctuated and was positively dependent on the vole supply during the same spring. In this region, there has also been a decline in vole numbers in recent decades, from high-amplitude cycles in the 1970s to subsequent low-amplitude cycles. Correspondingly, and as predicted, mean annual brood size of the owls also declined, although only during the third years of the vole cycle when vole supply in spring and brood size of the owls is at its highest level in high-amplitude cycles. We predict that in the long run the vole decline, associated with increasingly milder winters, and the reduction of the brood size of the owls, especially in years of high owl breeding success, will have serious implications for the population of great grey owls in Scandinavia.
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Affiliation(s)
- T. Hipkiss
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
- Bindevägen 5, SE-961 37 Boden, Sweden
| | - O. Stefansson
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
- Bindevägen 5, SE-961 37 Boden, Sweden
| | - B. Hörnfeldt
- Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden
- Bindevägen 5, SE-961 37 Boden, Sweden
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37
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Lande R, Engen S, Saether BE, Filli F, Matthysen E, Weimerskirch H. Estimating density dependence from population time series using demographic theory and life-history data. Am Nat 2008; 159:321-37. [PMID: 18707418 DOI: 10.1086/338988] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
For populations with a density-dependent life history reproducing at discrete annual intervals, we analyze small or moderate fluctuations in population size around a stable equilibrium, which is applicable to many vertebrate populations. Using a life history having age at maturity alpha, with stochasticity and density dependence in adult recruitment and mortality, we derive a linearized autoregressive equation with time lags from 1 to alpha yr. Contrary to current interpretations, the coefficients corresponding to different time lags in the autoregressive dynamics are not simply measures of delayed density dependence but also depend on life-history parameters. The theory indicates that the total density dependence in a life history, D, should be defined as the negative elasticity of population growth rate per generation with respect to change in population size, [Formula: see text], where lambda is the asymptotic multiplicative growth rate per year, T is the generation time, and N is adult population size. The total density dependence in the life history, D, can be estimated from the sum of the autoregression coefficients. We estimate D in populations of seven vertebrate species for which life-history studies and unusually long time series of complete population censuses are available. Estimates of D were statistically significant and large, on the order of 1 or higher, indicating strong density dependence in five of the seven species. We also show that life history can explain the qualitative features of population autocorrelation functions and power spectra and observations of increasing empirical variance in population size with increasing length of time series.
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Affiliation(s)
- R Lande
- Department of Biology, University of California at San Diego, La Jolla, California 92093, USA
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Population dynamics of pampas mice (Akodon azarae): signatures of competition and predation exposed through time-series modeling. POPUL ECOL 2008. [DOI: 10.1007/s10144-008-0103-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Christensen P, Ecke F, Sandström P, Nilsson M, Hörnfeldt B. Can landscape properties predict occurrence of grey-sided voles? POPUL ECOL 2008. [DOI: 10.1007/s10144-008-0077-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Miller N, Gerlai R. Quantification of shoaling behaviour in zebrafish (Danio rerio). Behav Brain Res 2007; 184:157-66. [PMID: 17707522 DOI: 10.1016/j.bbr.2007.07.007] [Citation(s) in RCA: 226] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 07/01/2007] [Accepted: 07/06/2007] [Indexed: 11/26/2022]
Abstract
Zebrafish has been a favourite of developmental biologists and numerous genetic tools have been developed for this species. In recent years, zebrafish has become an increasingly popular subject of neuroscientists and behavioural scientists. One of the typical characteristics of zebrafish is shoaling, individuals forming a tight group in which fish swim together. The biological mechanisms of social behaviours are complex and not well understood in vertebrates, and zebrafish, due to its highly social nature and the genetic tools developed for it, may represent an excellent animal model with which these mechanisms may be studied. Improvement of behavioural quantification methods would facilitate research in this area. We describe a custom software application that allows the precise quantification of several parameters of group cohesion in zebrafish. We also present three experimental examples to illuminate the use of our methodology, and show how group cohesion changes in response to manipulations of the environment.
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Affiliation(s)
- Noam Miller
- Department of Psychology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ont., Canada L5L 1C6.
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Blanchet S, Loot G, Bernatchez L, Dodson JJ. The disruption of dominance hierarchies by a non-native species: an individual-based analysis. Oecologia 2007; 152:569-81. [PMID: 17345104 DOI: 10.1007/s00442-007-0668-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
We studied the effects of the exotic rainbow trout (Oncorhynchus mykiss) on the performance and the dominance hierarchy of native Atlantic salmon (Salmo salar) at the group and individual level using laboratory and semi-natural experiments. At the group level, we compared the effects of interspecific and intraspecific competition (substitutive and additive design) on behavioural responses and growth of young-of-the-year Atlantic salmon. At the individual level, the same design was used to evaluate: (1) the temporal consistency of behavioural responses, dominance hierarchy and growth rate of Atlantic salmon; (2) the pattern of correlations between behaviours; and (3) the relationship between individual growth rate and behaviour. In the laboratory, group-level analyses revealed a weak but similar effect of rainbow trout and intraspecific competition on the behaviour and growth of Atlantic salmon. In contrast, individual-based analyses demonstrated that rainbow trout (but not intraspecific competition) strongly affected behavioural strategy, dominance hierarchy and growth trajectory of individual Atlantic salmon. Specifically, behaviours, dominance status and growth rate of salmon were temporally consistent in the intraspecific environment, while these patterns were disrupted when rainbow trout were present. Similarly, we found that rainbow trout strongly affected behavioural correlations and the relationships between individual growth rate and behaviour. The semi-natural experiments confirmed these results as interspecific competition affected relationships between individual growth rate of salmon, initial weight and activity index. Overall, individual-based analyses highlighted important mechanisms that were concealed at the group level, and that may be crucial to understand ecological and evolutionary consequences of exotic species. Moreover, these results demonstrated that competition with an exotic species disrupts the hierarchical relationship among native individuals and may therefore represent a potential for a shift in selective pressure.
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Affiliation(s)
- S Blanchet
- CIRSA & Québec-Océan, Département de Biologie, Pavillon Vachon, Université Laval, Ste Foy, Quebec, Canada
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LINDSTRÖM JAN, RANTA ESA, KOKKO HANNA, LUNDBERG PER, KAITALA VEIJO. From arctic lemmings to adaptive dynamics: Charles Elton's legacy in population ecology. Biol Rev Camb Philos Soc 2007. [DOI: 10.1111/j.1469-185x.2000.tb00061.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
Various predator-prey, host-pathogen, and competitive interactions can combine to cause density dependence in population growth. Despite this possibility, most empirical tests for density-dependent interactions have focused on single mechanisms. Here we tested the hypothesis that two mechanisms of density dependence, parasitism and a shortage of refuges, jointly influence the strength of density-dependent mortality. We used mark-recapture analysis to estimate mortality of the host species, the bridled goby (Coryphopterus glaucofraenum). Sixty-three marked gobies were infected with a copepod gill parasite (Pharodes tortugensis), and 188 were uninfected. We used the spatial scale at which gobies were clustered naturally (approximately 4 m2) as an ecologically relevant neighborhood and measured goby density and the availability of refuges from predators within each goby's neighborhood. Goby survival generally declined with increasing density, and this decline was steeper for gobies with access to few refuges than for gobies in neighborhoods where refuges were common. The negative effects of high density and refuge shortage were also more severe for parasitized gobies than for gobies free of parasites. This parasite has characteristics typical of emerging diseases and appears to have altered the strength of a preexisting density-dependent interaction.
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Affiliation(s)
- Graham E Forrester
- Department of Natural Resources Science, University of Rhode Island, Kingston 02881, USA.
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Abstract
Northern voles and lemmings are famous for their spectacular multiannual population cycles with high amplitudes. Such cyclic vole populations in Scandinavia have shown an unexpected and marked long-term decline in density since the early 1970s, particularly with a marked shift to lower spring densities in the early 1980s. The vole decline, mainly characterized by a strongly decreased rate of change in numbers over winter, is associated with an increased occurrence of mild and wet winters brought about by a recent change in the North Atlantic Oscillation. This has led to a decrease in winter stability and has shortened the period with protective snow cover, the latter considered as an important prerequisite for the occurrence of multiannual, high-amplitude cycles in vole populations. Although the vole decline is predicted to be negative for predators' reproduction and abundance, empirical data showing this are rare. Here we show that the dynamics of a predator-prey system (Tengmalm's owl, Aegolius funereus, and voles), have in recent years gradually changed from 3-4 yr, high-amplitude cycles towards more or less annual fluctuations only.
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Affiliation(s)
- Birger Hörnfeldt
- Department of Ecology and Environmental Science, Umeå University, 90187 Umeå, Sweden.
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Hellstedt P, Henttonen H. Home range, habitat choice and activity of stoats (
Mustela erminea
) in a subarctic area. J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2006.00072.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- P. Hellstedt
- Department of Biological and Environmental Sciences, University of Helsinki, Finland
| | - H. Henttonen
- Finnish Forest Research Institute, Vantaa Research Centre, Vantaa, Finland
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Hörnfeldt B. Long-term decline in numbers of cyclic voles in boreal Sweden: analysis and presentation of hypotheses. OIKOS 2004. [DOI: 10.1111/j.0030-1299.2004.13348.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Norrdahl K, Heinilä H, Klemola T, Korpimäki E. Predator-induced changes in population structure and individual quality ofMicrotusvoles: a large-scale field experiment. OIKOS 2004. [DOI: 10.1111/j.0030-1299.2004.12684.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Stenseth NC, Viljugrein H, Saitoh T, Hansen TF, Kittilsen MO, Bølviken E, Glöckner F. Seasonality, density dependence, and population cycles in Hokkaido voles. Proc Natl Acad Sci U S A 2003; 100:11478-83. [PMID: 14504382 PMCID: PMC208783 DOI: 10.1073/pnas.1935306100] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2002] [Indexed: 11/18/2022] Open
Abstract
Voles and lemmings show extensive variation in population dynamics regulated across and within species. In an attempt to develop and test generic hypotheses explaining these differences, we studied 84 populations of the gray-sided vole (Clethrionomys rufocanus) in Hokkaido, Japan. We show that these populations are limited by a combination of density-independent factors (such as climate) and density-dependent processes (such as specialist predators). We show that density-dependent regulation primarily occurs in winter months, so that populations experiencing longer winters tend to have a stronger delayed density-dependence and, as a result, exhibit regular density cycles. Altogether, we demonstrate that seasonality plays a key role in determining whether a vole population is cyclic or not.
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Affiliation(s)
- Nils Chr Stenseth
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1031 Blindern, N-0316 Oslo, Norway.
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