Luis-Miguel Chevin

Centre d’Ecologie Fonctionnelle et Evolutive, CNRS Montpellier, France

Stochastic evolutionary demography under a fluctuating optimum phenotype

[When and where]

Temporal environmental variation in natural systems includes a large component of random fluctuations, the magnitude and predictability of which are modified under current climate change. Environmental stochasticity strongly impacts ecology and population dynamics, notably by decreasing the long-run growth rate of a population, and increasing extinction risk. Environmentally driven fluctuating selection also determines the effect of genetic responses to selection on the mean fitness of a population, and influences the evolution of bet hedging and phenotypic plasticity. The temporal autocorrelation of the environment, which determines its predictability over different time scales, is an important modulator of these demographic and evolutionary effects. However, we still largely lack a theory that integrates these eco-evolutionary processes, accounting for environmental predictability. In particular, we need predictions not only for expectations of the processes, but also for their stochastic variances, which are especially important for extinction risk. I will present results of simple models where stochastic population dynamics arise from environmental fluctuations of the optimum phenotype for a quantitative trait. Assuming frequency- and density-independent selection on a polygenic trait, I will show how evolutionary quantitative genetics can be used to derive analytically the stochastic distribution of the population size at any time. Exact results under density-independent population growth will be compared to approximations under different forms of density-dependent regulation. These results will be illustrated by the scenario of evolutionary rescue in a stochastic environment. Finally, I will discuss how phenotypic plasticity modifies the eco-evolutionary outcomes of fluctuating selection.

luis-miguel.chevin[at]cefe.cnrs.fr

Invited talk Mini-symposium 5

Updated May 13, 2015, by Minus