Target size and optimal life history when individual growth and energy budget are stochastic

Ido Filin (1)

1 Department of Mathematics and Statistics

I extend my previous work on life history optimization when body mass is divided into reserves and structure components. Two important innovations are: (1) effect of finite target size on optimal structural growth; (2) incorporating reproduction in the optimization objective. I derive optimal growth trajectories and life histories, given that the individual is subject to both starvation mortality and exogenous hazards (e.g., predation). Because of overhead costs in building structural mass, it is optimal to stop structural growth close to the target size, and to proceed only by accumulating reserves. Higher overhead costs cause earlier cessation of structural growth and smaller final structures. Semelparous reproduction also promotes early cessation of structural growth, compared to when only survival to target size is maximized. In contrast, iteroparous reproduction can prolong structural growth, resulting in larger final structures than in either the survival or the semelparous scenarios. Increasing the noise in individual growth lowers final structural mass at small target sizes, but the effect is reversed for large target sizes. My results provide predictions for comparative studies. I outline important consequences of my results to additional important evolutionary questions: evolution of sexual dimorphism, optimization of clutch size and evolution of progeny and adult sizes.

Mots clés: Diffusion process; Energy-predation tradeoff; Hazard function; State-dependent life history

Ido Filin. Target size and optimal life history when individual growth and energy budget are stochastic. Journal of Theoretical Biology, 2010, 264 (2), pp.510. ⟨10.1016/j.jtbi.2010.02.031⟩. ⟨hal-00585802⟩