Costs and correlates of evolution of increased dispersal in Drosophila melanogaster

Abstract

Dispersal is a vital process that influences species distribution patterns and allows organisms to track favourable environmental conditions. Dispersal evolution is intimately linked with biological invasions and range shifts due to climate change. Hence it is important to understand the ecological and evolutionary consequences of dispersal. Studies on dispersal often focus on association of traits with dispersal, thereby neglecting how the traits themselves can change with evolution of dispersal. Here, I investigate the effects of dispersal evolution using populations of Drosophila melanogaster selected for increased dispersal. I find that evolution of increased dispersal leads to an increase in locomotion without affecting critical components of fitness such as fecundity and lifespan. Moreover, dispersal evolution does not lead to a change in body glucose and glycogen content. Finally, I show that, traits associated with increased dispersal do not deteriorate when selection pressures are relaxed. These findings imply that dispersal evolution entails no major costs and that higher dispersive phenotype can persist in populations even when dispersal is not advantageous. These findings coupled with the fact that dispersal is heritable, imply that populations can rapidly evolve higher dispersal under favorable conditions. Thus, the results of this study can improve our insights on processes like range shifts, invasions and response of populations to various environmental stresses including the effects of climate change.