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Capital and income breeding: the role of food supply

Stephens, P.A.; Houston, A.I.; Harding, K.C.; Boyd, I.L.; McNamara, J.M.

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Authors

A.I. Houston

K.C. Harding

I.L. Boyd

J.M. McNamara



Abstract

An aspect of life history that has seen increasing attention in recent years is that of strategies for financing the costs of offspring production. These strategies are often described by a continuum ranging from capital breeding, in which costs are met purely from endogenous reserves, to income breeding, in which costs are met purely from concurrent intake. A variety of factors that might drive strategies toward a given point on the capital–income continuum has been reviewed, and assessed using analytical models. However, aspects of food supply, including seasonality and unpredictability, have often been cited as important drivers of capital and income breeding, but are difficult to assess using analytical models. Consequently, we used dynamic programming to assess the role of the food supply in shaping offspring provisioning strategies. Our model is parameterized for a pinniped (one taxon remarkable for the range of offspring-provisioning strategies that it illustrates). We show that increased food availability, increased seasonality, and, to a lesser extent, increased unpredictability can all favor the emergence of capital breeding. In terms of the conversion of energy into offspring growth, the shorter periods of care associated with capital breeding are considerably more energetically efficient than income breeding, because shorter periods of care are associated with a higher ratio of energy put into offspring growth to energy spent on parent and offspring maintenance metabolism. Moreover, no clear costs are currently associated with capital accumulation in pinnipeds. This contrasts with general assumptions about endotherms, which suggest that income breeding will usually be preferred. Our model emphasizes the role of seasonally high abundances of food in enabling mothers to pursue an energetically efficient capital-breeding strategy. We discuss the importance of offspring development for dictating strategies for financing offspring production.

Citation

Stephens, P., Houston, A., Harding, K., Boyd, I., & McNamara, J. (2014). Capital and income breeding: the role of food supply. Ecology, 95(4), 882-896. https://doi.org/10.1890/13-1434.1

Journal Article Type Article
Acceptance Date Sep 10, 2013
Online Publication Date Apr 1, 2014
Publication Date Apr 1, 2014
Deposit Date May 9, 2014
Publicly Available Date Mar 28, 2024
Journal Ecology
Print ISSN 0012-9658
Publisher Ecological Society of America
Peer Reviewed Peer Reviewed
Volume 95
Issue 4
Pages 882-896
DOI https://doi.org/10.1890/13-1434.1
Keywords Capital breeding, Energetics of reproduction, Fasting, Foraging cycle, Income breeding, Lactation, Pinnipeds, Seasonal environments.

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