A reexamination of the negative assortative mating phenomenon and its underlying mechanism in Drosophila melanogaster

Abstract

Averhoff and Richardson [(1974) Behav. Genet.4:207–225] reported a trend toward negative assortative mating in Drosophila melanogaster during the course of inbreeding. These authors proposed that the underlying mechanism was based on pheromone polymorphism and male selection. Mass mating experiments were carried out to verify their hypothesis, detailed behavior observations were made to identify the underlying mechanism, and sex pheromone composition and variation were examined by using gas chromatography-mass spectrometry analysis. The results showed that negative assortative mating is not a general phenomenon. Although male pheromones are probably polymorphic, female pheromones are not. We found no evidence for male selection as predicted by Averhoff and Richardson. It is argued that the most parsimonious mechanism underlying negative assortative mating is similar to one proposed by Bryant [(1979) Behav. Genet.9:249–256], which was based on interstrain differences in female reluctancy and male vigor.