Adaptive shifts in female mating preferences within in a fiddler crab population (#425)
Females of several species can temporally alter their mating preferences depending on the benefits of mating with specific males. Females of the banana fiddler crab (Uca mjoebergi) adjust their mating preferences for male size depending on the time in the mating period. Those that mate early, select larger males since they have cooler burrows that slow incubation; those mating later, select smaller males since their warmer burrows speed up incubation. This results in all females releasing larvae at the optimal highest spring tide. This pattern, however, is based on crabs living in the highest intertidal zone. In this study we examine the pattern of female preferences throughout the intertidal zone. We show that females living in the lower intertidal zones are less restricted by both temperature and tidal inundation and are able to release their larvae over a much longer window of time. Here we show that females timed their mating and altered their mate choices depending on their position in the intertidal zone. Females higher on the mudflat preferentially mated with larger males early in the mating cycle and smaller males later in the mating cycle. This effect became less evident in the crabs living further down the mudflat and, at the lowest site, females showed no change in preference for male size over the duration of the mating period.