A genetic and molecular analysis of mating choice in D. simulans. Rui Sousa-Neves, Youngmin Chu, Emma Yang, Joseph Schinaman, Sebastian Chahda. Biol, Case Western Reserve Univ, Cleveland, OH.

   Female mating choice is an ancient and wide spread process of decision-making in the animal kingdom that allows females to recognize and mate with conspecific males and reject males of other species. Besides its evolutionary significance, this behavior serves as a platform to identify genes and circuits required for decision-making. Drosophila simulans, and Drosophila sechellia are three closely related species of Drosophila with very similar genomes and a marked difference for the males that they prefer. Here we analyzed F2 hybrids between D. simulans and D. sechellia for their ability to mate or reject D. simulans males. Our results show that a set of dominant genes are required for this choice. The X- chromosome bears two of these genes, Mate choice XA (Macho-XA) and Mate choice XB (Macho-XB). In addition, two other dominant genes are localized on the second and third chromosomes. We genetically and molecularly mapped the two X- chromosome genes to relatively small intervals. In addition, we found that sex appeal segregates as one or two autosomal genes suggesting that Macho-2 and Macho-3 encode sex appeal.