Temporal and spatial variation in female mating preferences in a fiddler crab

Female mating preferences can vary temporally, with females choosing different males at different times; and spatially, with females in different populations preferring different males. This level of complexity is now well established, but we know of no evidence for a mosaic of female preferences within a single population. Here we show that, in the banana fiddler crab, Uca mjoebergi, female preferences vary both temporally and spatially. Females living in the high inter-tidal zone changed their mating preference for male size over the duration of the 9-day mating period every semi-lunar cycle: early mating females selected larger males with cooler burrows, slowing embryonic development; those mating later, selected smaller males with warmer burrows, accelerating development. Females living lower in the inter-tidal zone, however, did not show this temporal variation: they select the same sized males throughout the mating period. It is only in the high inter-tidal zone, at the start of the fortnightly mating period, that large size confers a mating advantage to males.