Evolution of sociability: genome scans and gene validation

Sociability, defined as individuals' tendencies to affiliate with conspecifics, has positive associations with fitness in animals as well as with health, well-being, and longevity in humans. Despite its importance, we still have limited information about natural genetic variation in sociability. As part of a long-term initiative to address this knowledge gap, we quantified changes in allele frequencies in adult fruit flies (Drosophila melanogaster) from lineages that we artificially selected to diverge in sociability. Based on our genomic analyses, we generated a short list of 226 single nucleotide polymorphisms (SNPs) representing 169 candidate genes influencing variation in sociability. We also made a shorter list of 41 SNPs from 36 genes that showed the largest average divergence between the low and high sociability lineages. Experiments using knockdowns of 19 of the candidate sociability genes revealed that 18 of them significantly affected sociability, though some effects were sex-specific. Our results provide important insights into a quantitative trait central to the lives of many animals including humans.