A quantitative genetics approach to the evolution of phenotypic (co)variance under limited dispersal, with an application to socially synergistic traits

Abstract

AbstractDarwinian evolution consists of the gradual transformation of heritable quantitative traits due to natural selection and the input of random variation by mutation. Here, we use a quantitative genetics approach to investigate the coevolution of multiple traits under selection, mutation, and limited dispersal. We track the dynamics of trait means and variance-covariances between traits that experience frequency-dependent selection. Assuming a multivariate-normal trait distribution, we recover classical dynamics of quantitative genetics, as well as stability and evolutionary branching conditions of invasion analyses, except that due to limited dispersal, selection depends on indirect fitness effects and relatedness. In particular, correlational selection that associates different traits within-individuals depends on the fitness effects of such associations between-individuals. These kin selection effects can be as relevant as pleiotropy for correlation between traits. We illustrate this with an example of the coevolution of two social traits whose association within-individual is costly but synergistically beneficial between-individuals. As dispersal becomes limited and relatedness increases, associations between-traits between-individuals become increasingly targeted by correlational selection. Consequently, the trait distribution goes from being bimodal with a negative correlation under panmixia to unimodal with a positive correlation under limited dispersal. More broadly, our approach can help understand the evolution of intra-specific variation.