Migration of cabbage butterfly (Pieris brassicae):Influence of environmental factors on dispersal

Abstract

Dispersal and migration play a crucial role as evolutionary adaptations, allowing organisms to escape adverse conditions, exploit other habitats and maintain gene flow between populations. Nevertheless, migratory behaviour is often difficult or impossible for organisms that have already locally adapted to a certain environment. One model of this balance between migration and local adaptation is the large white butterfly, Pieris brassicae (Lepidoptera: Pieridae). Indigenous to regions as varied and often improbable as Europe and Asia, this pretty little butterfly can also travel up to hundreds of kilometres in a single year. Conversely, populations of P. brassicae possess local adaptations in response to downstream selection revealed by the regulation of overwintering life stages based upon geographic variation in day length despite high vagility. During short autumn days, northern populations go into diapause but southern north remain active for the year. These local adaptations imply historical stability within regional populations,
but these results may only counteract a single broad range event.