Behaviour 2019
Frequency-Dependent Selection and Selection on Network Structure Depend on Indirect Genetic Effects
Eric W. Wice, Julia B. Saltz. Rice University, Houston, TX, United States

The genotypic composition of social groups and how it affects individuals’ fitness -i.e., indirect genetic effects (IGEs)- is thought to be an important driver of variation in social selection. Studying the quantitative genetic basis of social group structure and its effects on fitness is necessary for understanding how groups respond to social selection. Two ways that the genotypic composition of social groups and IGEs can impact social selection is via frequency-dependent selection, and selection on social network structure. Using replicate genotypes of D. melanogaster flies, we manipulated the genotypic composition of social groups, and measured social network structure and multiple components of fitness for individuals within groups. We found positive frequency-dependent selection on measures of females’ fitness, and frequency-dependent selection varied with indirect genetic effects of social groupmates. We also found selection on measures of individuals’ social network positions, and this selection also varied depending on indirect genetic effects. These findings suggest variation in social selection can be driven by variation in the social context individuals experience.