Research on Drosophila serrata has shown that male members of the species tend to increase in sexual attractiveness from one generation to the next. The landmark finding, however, is derived from the fact that though this does increase each subsequent generations fitness in regards to mating, their is a point at where the attractiveness becomes a "turn off." The reasoning lies in the pheromones released by the flies, where while particularly intoxicating to the female Drosophila s., after seven generations, the increases stop, and female flies no longer care about the overly abundant sexual stylings of the fly. Further research has shown that in continued generations of naturally mated flies, the overall effect of artificially bolstering males with pheromones ears to a 50% decrease in less then six generations. NY Times
