Capital and income breeding: the role of food supply

Abstract

Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. 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 capitalincome 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.

Bio‐energetic modeling of medium‐sized cetaceans shows high sensitivity to disturbance in seasons of low resource supply

“…, Stephens et al. ). Due to this extreme lifestyle, disturbance affects such species differently compared to a medium‐size cetacean like a pilot whale, which continues to feed throughout the year.…”

Offspring sex ratio in mammals and the Trivers‐Willard hypothesis: In pursuit of unambiguous evidence

“…The two meta-analyses reached different conclusions about the most appropriate measure of maternal condition. The capital-income breeder continuum [34] could nevertheless guide researchers in their choice of metric to use as proxy of maternal condition. Furthermore, the relationship between female dominance and access to food resources varies among ungulates, since in some species dominant females may have few opportunities to monopolize access to preferred forage [33].…”

An ordination of life histories using morphological proxies: capital vs. income breeding in insects

“…The concepts of capital and income breeding were first applied (Drent and Daan 1980, Stearns 1992, Jönsson 1997, and are still widely used (Stephens et al 2009(Stephens et al , 2014Sénéchal et al 2011, Warne et al 2012 in vertebrate ecology. Reproduction based on previously stored resources is referred to as capital breeding whereas in income breeders, reproduction is based on concurrent food intake.…”