Does Density Dependent Selection act as a driving force for reproductive isolation?

Abstract

Reproductive isolation in a population is not directly favored but arises as a byproduct of differential selection on traits. Local environment plays an important role in shaping the life history of the populations. If two populations of the same species get adapted to two different types of local environments, as a result of differential selection on traits, differ- ent traits are expected to evolve in the population. We investigated premating and post mating prezygotic reproductive isolation in Drosophila melanogaster population adapted to larval crowding for more than 200+ generations. A competitive resource-based density dependent selection such as larval crowding can affect a number of adult traits in a life of holometabolous insect like Drosophila melanogaster. There exist differences in repro- ductive traits like increased courtship frequency, increased relative testis size and in certain developmental traits. These populations showed no evidence of pre-mating and post mating reproductive isolation inferred via assortative mating assay.