TIME CONSTRAINTS AND MULTIPLE-CHOICE CRITERIA IN THE SAMPLING BEHAVIOR AND MATE CHOICE OF THE FIDDLER-CRAB, UCA ANNULIPES

Active female sampling occurs in the fiddler crab Uca annullipes. Fema les sample the burrows of several males before remaining to mate in th e burrow of the chosen partner. Females time larval release to coincid e with the following nocturnal spring tide and must therefore leave su fficient time for embryonic development after mating. Here we show how this temporal constraint on search time affects female choosiness, We found that, at the start of the sampling period (when time constraint s are minimal), females selectively sample the larger males in the pop ulation. Towards the end of the sampling period (when the temporal con straints increase the costs of sampling), females are less selective. Furthermore, we suggest that the number of males sampled (and other in dices of ''sampling effort'') may not be reliable indicators of female choosiness and may not reflect the strength of female mating preferen ces under certain conditions. Burrow quality also emerged as an import ant criterion in final mate choice. Burrow structure potentially influ ences reproductive success, and mate acceptance based on burrow struct ure appears to involve a relatively invariant threshold criterion. Sin ce there is no relationship between male size and burrow quality, fema les are using at least two independent criteria when choosing potentia l mates. We envisage mate choice as a two-stage process. First, female s select which males to sample based on male size. They then decide wh ether or not to mate with a male based on burrow features. This sampli ng process explains how two unrelated variables can both predict male mating success.