Reducing error in reproductive timing caused by temperature variation: interspecific differences in behavioural adjustment by fiddler crabs

Abstract

Many organisms time reproduction with physical and biological cycles that affect offspring survival. In the marine environment, a common pat- tern is the release of planktonic larvae during large- amplitude nocturnal tides, which may reduce losses due to predation. However, if the duration of embry- onic development depends on temperature, changes in temperature can lead to errors in timing. Organ- isms may reduce such errors either by changing the timing of onset of incubation or by selecting the temperatures to which embryos are exposed. We conducted field and laboratory experiments with 2 species of fiddler crabs to examine the effects of temperature and temperature variation on the timing of larval release and synchrony of release among females. As expected, the duration of incubation increased with decreasing temperature in both spe- cies. In the field when temperature was low, Uca terpsichores released larvae earlier than expected, indicating that shifts in timing of mating reduced potential errors in timing of release. However, when temperature changed during incubation, accuracy and precision in the timing of release decreased. U. deichmanni maintained timing and synchrony of release despite variable temperature in the field, but in cold water in the laboratory, they incubated eggs longer than in the field and released larvae late. These differences suggest that U. deichmanni regu- lates the incubation period in the field. U. terpsi- chores may be less able than U. deichmanni to adjust to rapid variation in temperature that may accom- pany climate change, which could result in large- scale interspecific differences in larval survival and recruitment.