Population level consequences of facultatively cooperative behaviour in a stochastic environment

Busana, Michela, Childs, Dylan Z., Burke, Terrence A., Komdeur, Jan, Richardson, David S. and Dugdale, Hannah L. (2022) Population level consequences of facultatively cooperative behaviour in a stochastic environment. Journal of Animal Ecology, 91 (1). pp. 224-240. ISSN 0021-8790

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Abstract

1. The social environment in which individuals live affects their fitness and in turn population dynamics as a whole. Birds with facultative cooperative breeding can live in social groups with dominants, subordinate helpers that assist with the breeding of others, and subordinate non-helpers. Helping behaviour benefits dominants through increased reproductive rates and reduced extrinsic mortality, such that cooperative breeding might have evolved in response to unpredictable, harsh conditions affecting reproduction and/or survival of the dominants. Additionally, there may be different costs and benefits to both helpers and non-helpers, depending on the time-scale. For example, early-life costs might be compensated by later-life benefits. These differential effects are rarely analysed in the same study. 2. We examined whether helping behaviour affects population persistence in a stochastic environment and whether there are direct fitness consequences of different life-history tactics adopted by helpers and non-helpers. 3. We parameterised a matrix population model describing the population dynamics of female Seychelles warblers Acrocephalus sechellensis, birds that display facultative cooperative breeding. The stochastic density-dependent model is defined by a (st)age structure that includes life-history differences between helpers and non-helpers and thus can estimate the demographic mechanisms of direct benefits of helping behaviour. 4. We found that population dynamics are strongly influenced by stochastic variation in the reproductive rates of the dominants, that helping behaviour promotes population persistence and that there are only early-life differences in the direct fitness of helpers and non-helpers. 5. Through a matrix population model, we captured multiple demographic rates simultaneously and analysed their relative importance in determining population dynamics of these cooperative breeders. Disentangling early-life versus lifetime effects of individual tactics sheds new light on the costs and benefits of helping behaviour. For example, the finding that helpers and non-helpers have similar lifetime reproductive outputs and that differences in reproductive values between the two life-history tactics arise only in early life suggests that overall, helpers and non-helpers have a similar balance of costs and benefits when analysing direct benefits. We recommend analysing the consequence of different life-history tactics, during both early life and over the lifetime, as analyses of these different time frames may produce conflicting results.

Item Type: Article
Additional Information: Funding Information: The authors thank Nature Seychelles and their staff for allowing us to collect data on Cousin Island Nature Reserve and for providing accommodation during our work; the Seychelles Bureau of Standards for providing permission for fieldwork; NWO (grant 854.11.003 to J.K.), the Academy Ecology Fund (dossier 0205510763 to M.B.), the Academy Fund for Behavioural Research (dossier 0205510782 to M.B.) at KNAW, and NERC (fellowship NE/I021748/1 to HD, NE/F02083X/1 to DR, and NE/K005502/1, and NE/P011284/1 to D.S.R. and H.L.D.) for financial support. The authors grateful to all the members of the warbler group, Susanne Schindler, Sarah Cubaynes, Jean‐Michel Gaillard, David Koons and three anonymous reviewers for useful suggestions that improved the manuscript. They also thank the Center for Information Technology of the University of Groningen for their support and for providing access to the Peregrine high performance computing cluster. Publisher Copyright: © 2021 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.
Uncontrolled Keywords: bayesian analyses,cooperative breeding,direct fitness benefits,environmental stochasticity,group living,life-history tactics,matrix population model,population predictions,ecology, evolution, behavior and systematics,animal science and zoology ,/dk/atira/pure/subjectarea/asjc/1100/1105
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 26 Nov 2021 01:40
Last Modified: 17 Jan 2022 10:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/82358
DOI: 10.1111/1365-2656.13618

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