Behavioural traits correlated with evolution of increased dispersal in laboratory populations of Drosophila melanogaster

Abstract

Dispersal is an important phenomenon that helps organisms escape stressful conditions. Evolution of dispersal can help organisms in keeping up with an ever-changing environment, especially with decreasing habitat qualities, increasing habitat fragmentation and human encroachment. In our lab, we have been selecting for dispersal in populations of D. melanogaster and have observed that the lines selected for dispersal have evolved a greater tendency to leave their habitat as well as move to a greater distance. The present study uses these populations to examine the effects of dispersal evolution on three behavioural traits which can contribute significantly to an individual's Darwinian fitness, namely, aggression, exploration and mating behaviour. The populations that had evolved greater dispersal were found to be significantly more aggressive and exhibited greater exploratory behaviour than the corresponding controls. However, there were no differences in mating behaviours of the dispersal-selected and the control lines. Further, despite the existence of very different kinds of selection pressures on the two sexes during selection for dispersal, sex-specific differences in mating behaviours did not evolve in the selected lines. Understanding the behavioural traits that can change due to selection for dispersal leads to a better appreciation of dispersal evolution. This in turn becomes useful in investigating various ecological phenomena like the spread of invasive species, community composition, gene flow in fragmented populations, etc.