SREL Reprint #3323

Trade-offs between growth and maturation: the cost of reproduction for surviving environmental extremes

Thomas M. Luhring1,2 and Ricardo M. Holdo1

1Division of Biological Sciences, University of Missouri, Columbia, MO, USA
2Savannah River Ecology Laboratory, Aiken, SC, USA

Abstract: Life-history trade-offs and the costs of reproduction are central concepts in evolution and ecology. Episodic climatic events such as drought and extreme temperatures provide strong selective pressures that can change the balance of these costs and trade-offs. We used size-structured matrix models parameterized from field and laboratory studies to examine the effect of periodic drought on two species of aquatic salamanders (greater siren, Siren lacertina; lesser siren, Siren intermedia) that differ in size at reproduction and maximum body size. Post-drought body size distributions of the larger species (S. lacertina) are consistent with size-dependent mortality. Smaller individuals were extirpated from the population during each drought while large animals persisted, a pattern that contrasted with that seen in several ectotherms. This appears to be largely explained by estivation proficiency and a positive relationship between body size and estivation potential. Increased body size, however, may come at the cost of fecundity and maturation rate compared to a closely related congener. The cost of somatic allocation in this case may manifest itself via reduced per-capita competitive ability, which (at least in simulation studies) allows the smaller, fast-maturing species to outcompete the larger, slow-maturing species when drought is minimal or nonexistent.

Keywords: Body size, Life-history strategy, Reproductive allocation, Estivation, Drought, Size structure

SREL Reprint #3323

Luhring, T. M. and R. M. Holdo. 2015. Trade-offs between growth and maturation: the cost of reproduction for surviving environmental extremes. Oecologia 178(3): 723-732.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).