Effect of presence of kin on dispersal and social behaviours in Drosophila melanogaster

Abstract

Behaviour can be altered by the presence of kin, and this is seen in multiple organisms. This phenomenon is comparatively less studied in organisms that do not show group-living behaviour, like Drosophila melanogaster. Our study examines how the presence of kin affects behaviours in Drosophila melanogaster, with a focus on how sex and mating status modulate these responses. We study dispersal, aggregation, aggression, and mating behaviours in both a mate choice and nochoice setup. We see that mating behaviours can be kin-biased depending on the context in which mates interact. We also see that having been previously mated leads to closer aggregation between related same-sex groups, and virgin flies do not show this behaviour. We provide the first experimental proof that mating status and relatedness can interact to modulate dispersal propensity, with related groups of flies dispersing less than unrelated groups when mated but more when virgins. Mating also leads to reduced dispersal speed and increased rest levels of females, which has further implications in spatial sorting of populations. Our study shows that traditionally ‘non-social’ organisms like the fruit fly can be used as models to understand social behaviour between kin. We advocate for further experimental studies to elucidate the motivation behind complex group behaviours such as those we capture in our work.