Evolution of the genetic covariance between male and female components of mate recognition: an experimental test

The evolution of a positive genetic correlation between male and female com ponents of mate recognition systems will result as a consequence of assorta tive mating and, in particular, is central to a number of theories of sexua l selection. Although the existence of such genetic correlations has been i nvestigated in a number of taxa, it has yet to be shown that such correlati ons evolve and whether they may evolve as rapidly as suggested by sexual se lection models. In this study, I used a hybridization experiment to disrupt natural mate recognition systems and then observed the subsequent evolutio nary dynamics of the genetic correlation between male and female components for 56 generations in hybrids between Drosophila serrata and Drosophila bi rchii. The genetic correlation between male and female components evolved f rom 0.388 at generation 5 to 1.017 at generation 37 and then declined to -0 .040 after a further 19 generations. These results indicated that the genet ic basis of the mate recognition system in the hybrid populations evolved r apidly. The initial rapid increase in the genetic correlation was consisten t with the classic assumption that male and female components will coevolve under sexual selection. The subsequent decline in genetic correlation may be attributable to the fixation of major genes or, alternatively, may be a result of a cyclic evolutionary change in mate recognition.