Meeting Abstract

P1.68  Tuesday, Jan. 4  Do female soldier flies select for longer copulations by increasing their investment in number of eggs laid? BARBOSA, F.A.; University of Missouri fabdm2@mail.missouri.edu

Cryptic female choice (CFC) is a female-controlled postcopulatory process that favors paternity by preferred males when the female has mated multiply. Although there is substantial indirect evidence that CFC is widespread, it remains relatively understudied. CFC has several potential mechanisms; one possibility is that females lay more eggs after mating with preferred males. In a previous study, I demonstrated that CFC occurs in the soldier fly Merosargus cingulatus: females select against males that do not perform courtship by not ovipositing after mating with them. CFC may also be taking place among males that do provide courtship, as there is substantial variation in copulation duration. Males of this species perform courtship during the entire duration of copulation. Females mate and oviposit multiple times. I tested if females of the soldier fly M. cingulatus exert CFC on copulation duration by laying more eggs after mating with males that mate for longer. Males were placed in a field enclosure containing oviposition substrate, and submitted to one of two density treatments that allowed manipulation of copulation duration. For both treatments, I introduced a female to the enclosure, allowed the pair to mate and the female to oviposit, video-recorded the copulations and collected the eggs laid. The different densities resulted in significantly different copulation durations for each treatment. However, there were no significant differences between the number of eggs laid by females of the two groups, suggesting that they are not favoring longer copulations by laying more eggs. It is possible that females are selecting for longer copulations with different mechanisms, such as increasing the number of eggs sired by males that mate for longer. I am currently investigating this possibility.