Thesis

Multiple paternity : a life-history strategy for porcelain crabs in the face of rising temperatures

Multiple paternity is widespread across many taxa including birds, insects and marine species. Despite multiple paternity being rare among studied crustaceans, a study found that -93% of female porcelain crabs, Petrolisthes cinctipes, mate with more than one male and produce broods of mixed paternity. No explanation has been given to the reason of why multiple paternity is prolific in P. cinctipes, or what function polyandry may serve for crabs in general to my knowledge. In order to identify potential advantages of multiple paternity in P. cinctipes, brood survival differentials were measured under ambient conditions and after a heat-shock. Microsatellite profiling was used to distinguish multiple from single paternity and compared to brood survival, in the presence or absence of a heatshock. When exposed to a heat-shock, single-sired broods experience a significant drop in mean brood hatching %, compared to multiply-sired broods. Multiply sired broods also show a substantial, but non-statistically significant, mean difference in mean hatching % between conditions, compared to single-sired broods. Results suggest that multiple paternity reduces embryo survival variance between ambient and heat-shock conditions and that multiple mating could be an advantage for P. cinctipes in the high-intertidal zone.

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