SEXUAL ISOLATION BETWEEN DROSOPHILA-MELANOGASTER FEMALES AND DROSOPHILA-SIMULANS MALES - MALE MATING PROPENSITIES VERSUS SUCCESS IN HYBRIDIZATION

Genetic variation has been found in males of a D. simulans population for their eagerness to hybridize with D. melanogaster females. In a se arch for traits involved in this hybridization, males of D. simulans w ere tested for mating speed and sexual vigour. Between-male difference s were detected in both sexual traits, but no relationship was noticed between them, nor with the frequency of hybridization. Thus male mati ng propensities appear to be unrelated to the breakdown of sexual isol ation between these sibling species.