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Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem

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...

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Autores principales: Fauteux, Dominique, Stien, Audun, Yoccoz, Nigel G., Fuglei, Eva, Ims, Rolf A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8449336/
https://www.ncbi.nlm.nih.gov/pubmed/34504000
http://dx.doi.org/10.1073/pnas.2106635118
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author Fauteux, Dominique
Stien, Audun
Yoccoz, Nigel G.
Fuglei, Eva
Ims, Rolf A.
author_facet Fauteux, Dominique
Stien, Audun
Yoccoz, Nigel G.
Fuglei, Eva
Ims, Rolf A.
author_sort Fauteux, Dominique
collection PubMed
description 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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spelling pubmed-84493362021-10-04 Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem Fauteux, Dominique Stien, Audun Yoccoz, Nigel G. Fuglei, Eva Ims, Rolf A. Proc Natl Acad Sci U S A Biological Sciences 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. National Academy of Sciences 2021-09-14 2021-09-09 /pmc/articles/PMC8449336/ /pubmed/34504000 http://dx.doi.org/10.1073/pnas.2106635118 Text en Copyright © 2021 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Biological Sciences
Fauteux, Dominique
Stien, Audun
Yoccoz, Nigel G.
Fuglei, Eva
Ims, Rolf A.
Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title_full Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title_fullStr Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title_full_unstemmed Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title_short Climate variability and density-dependent population dynamics: Lessons from a simple High Arctic ecosystem
title_sort climate variability and density-dependent population dynamics: lessons from a simple high arctic ecosystem
topic Biological Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8449336/
https://www.ncbi.nlm.nih.gov/pubmed/34504000
http://dx.doi.org/10.1073/pnas.2106635118
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