gistfile1.txt

Timing specific reproductive events with changes in the environment often ensures the maximum survival of many organisms and their offspring. Thus, adapting to variable conditions in order to maintain the same timings is crucial to the fitness of the species. Fiddler crabs were chosen to examine the behavior of organisms in timing specific life events for their well-known reproductive behavior and abundance. The common timing of larval release of fiddler crabs was found to be during nocturnal high amplitudes in order to minimize predation and maximize distribution. If incubation and developmental durations are affected by variations in temperature, larval release timings might be mismatched with the targeted event, resulting in less viability. Variations in temperature also cause cold, nutrient rich, deep source water to be moved to the surface in a phenomenon called upwelling, which also affect the survival of planktonic larvae. Two fiddler crab species, Uca terpsichores and Uca deichmanni, were studied in order to determine if and how they adapt to such variations in reproductive conditions in order to hit the optimal timing for larval release. By comparing amount of predation of brine shrimp and larvae during day and night as well as upwelling, it was found that the risk of predation was higher during the day and during upwelling. Through monitoring courtship occurrences across a long period of time and logging the environmental conditions, it was found that U. deichmanni consistently courted at times matching tidal amplitude, regardless of temperature and upwelling, whereas U. terpsichores had changed its courtship timings between locations and environmental conditions. To determine the ability to keep larval release timings, the incubation periods of U. deichmanni and U. terpsichores were monitored in various temperatures both in the field and in the lab. It was found that both species had longer incubation period as expected. U. terpsichores had low synchrony in larval release timings, while U. deichmanni had very synchronized and well-timed larval releases, but released late with low temperatures. These differences suggest a difference in timing strategies, ultimately results in a difference in offspring survival and fitness.