Capital Breeding and Allocation to Life History Demands are Highly Plastic in Lizards at the Sevilleta National Wildlife Refuge, New Mexico: Experimental Study



The use of stored resources to fuel reproduction, growth and maintenance to balance variation in nutrient availability is common to many organisms. The degree to which organisms rely upon stored resources in response to varied nutrients, however, is not well quantified. Through stable isotope methods we quantified the use of stored versus incoming nutrients to fuel growth, egg and fat body development in lizards under differing nutrient regimes. We found that the degree of capital breeding is a function of an individual’s body condition. Furthermore, given sufficient income lizards in poor condition can allocate simultaneously to storage, growth, and reproduction, which allowed them to catch up to better conditioned animals. In a parallel, inter-specific survey of wild lizards we found that the degree of capital breeding varied widely across a diverse community. These findings demonstrate that capital breeding in lizards is not simply a one-way flow of endogenous stores to eggs, but is a function of the condition state of individuals and the availability of nutrients during both breeding and non-breeding seasons. Here we explore the implications of these findings for our understanding of capital breeding in lizards and the utility and value of the capital-income concept in general. 

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Sunday, July 1, 2007 to Sunday, June 1, 2008