Pre-zygotic isolation has been recognized as the primary form of incipient speciation, with behavioral isolation as one of its most significant manifestations. In spite of intensive research on behavioral isolation, its molecular mechanism is still poorly understood. We present microarray data from two morphs, black (OH) and brown (HK), of Drosophila elegans. Since only OH females show strong preference to mate with same type of males, these two morphs provide a model system for investigations into the incipient stage of speciation.

We analyzed the expression profiles from heads of mated OH females and non-mated females of both morphs. Subsequent analysis of candidate genes by GoMiner showed that OH unique genes were enriched in the visual system related categories, and these categories were still enriched with candidate genes whose expression levels were modified after mating. These results suggest that Drosophila elegans might use visual cues mainly as mate recognition.