Evaluating life history theory and the consequences of reproductive strategy for population fluctuations

• Jennifer L. Williams

Abstract
Organisms have evolved a variety of mechanisms to maximize individual fitness in the face of environmental stochasticity that may also serve to buffer population fluctuations. Life history strategies for reproduction, including whether to produce all offspring at once (semelparity) or to spread out the reproductive effort across several bouts (iteroparity), can lead to important consequences for population persistence. While much theory predicts which strategy should be optimal for individuals, few empirical tests exist. The proposed research will use stochastic population models compiled from published and unpublished data of species that exhibit facultative semelparity to address two unresolved issues in evolutionary biology and population ecology: when can iteroparity buffer population fluctuations and do life history predictions match the observed strategy with realized levels of stochasticity? This project will help to refine current life history theory on semelparity and iteroparity, and will clarify the connection between selection pressures on individuals and the consequences for population persistence. Understanding a mechanism that can buffer population fluctuations will also contribute to predictions of which species may be more vulnerable to increased climate variability. Support from NCEAS will be crucial for gathering the volume of data necessary to conduct this research, and collaborations with resident and visiting ecologists will enhance not only this project but initiate new research.