Sexual isolation between Drosophila melanogaster females and D. simulans males. II. Influence of female receptivity on hybridization

Abstract

Hybridization between Drosophila melanogaster females and D. simulans males was measured in sympatric and allopatric populations of these sibling species by means of nonchoice tests. Greater sexual isolation was found in allopatric populations over sympatric ones. Notable age differences at which females reached sexual maturity were detected in the D. melanogaster populations. Females with an earlier sexual maturity also showed greater receptivity. Remarkably, female receptivity was the main factor accounting for frequency of hybridization. The role that both male and female mate propensities and discrimination abilities play in natural selection for sexual isolation is discussed. Key words: sexual isolation, Drosophila, female receptivity, hybridization.