Investigating the genetic basis of natural variation in sociability within Drosophila melanogaster

Abstract

Sociability is an individual’s tendency to associate with conspecifics in a non-aggressive manner. Sociability can manifest in the formation of social groups that can reduce predation risk and increase feeding success. Studies of social behaviour in insects are typically through the lens of classically know social insects, however many insect species that have been long thought as non-social have been shown to exhibit social behaviour, in particular Drosophila. A previous experiment evolved lineages of high and low sociable fruit flies (Drosophila melanogaster) following 25 generations of artificial selection, after which RNA and DNA was extracted and sequenced. The main goal of this thesis was to integrate analyses of differential gene expression, transcript usage and population genomics to investigate the genetic architecture of sociability in Drosophila. I developed a pipeline to perform differential gene expression analysis by modelling gene expression using a generalized linear mixed-effect model. Here I found a total of 327 genes differentially expressed and 174 genes differentially expressed between the low and high sociable lineages. Next, I developed a pipeline to perform differential transcript usage analysis using a generalized linear mixed-effect model to model transcript usage. I found 619 genes to have transcripts with differential usage and 190 genes to have transcripts with differential usage between the low and high sociable lineages. Lastly, I developed a pipeline for population genomics to identify regions of the genome under selection. I identified genes that are likely under selection and the overlap between these genes and genes/transcripts found to be differentially expressed/used. Overall, I identified potential genes that are involved in the genetic architecture of sociability and can be further candidate tested.