【動物行動】ジンバブエ由来のショウジョウバエのメスが同郷のオスを好む理由

The tendency of female fruit flies from Zimbabwe populations to mate with Zimbabwe males and not with those from other regions could be partly explained by the levels of a certain pheromone present in male fruit flies. The study, published in the journal Scientific Reports, adds to our understanding of the sensory processes involved in speciation. The early stages of speciation have been observed between fruit fly (Drosophila melanogaster) populations from Zimbabwe and those from the rest of the world, but the reasons for this have remained unclear. Jean-Francois Ferveur and colleagues studied the mating behaviour of eight fruit fly populations, two from Zimbabwe and six from other regions. Zimbabwe strains showed significant sexual isolation from other strains due to Zimbabwe females discriminating against cosmopolitan males. The mating frequency of Zimbabwe females is negatively correlated with the male’s level of 7-tricosene (7-T), a cuticular hydrocarbon that can act as a sex pheromone, the authors report. Conversely, cosmopolitan females tend to favour males with higher 7-T levels. The authors also reveal two genes that appear to govern these hydrocarbons but show they are not directly involved in female mating choice. The work highlights the role of cuticular hydrocarbons such as 7-T in mating patterns but the authors suggest there are probably further differences between the strains that contribute to the pheromone-driven sexual isolation shown here.