Kerr Kecia A, Christy John H, Joly-Lopez Zoé, Luque Javier, Collin Rachel, Guichard Frédéric
Department of Biology, McGill University, Montréal, Québec, Canada; Smithsonian Tropical Research Institute, Balboa, Ancon, Panama, Panama; McGill-STRI Neotropical Environment Option (NEO), McGill University, Montréal, Québec, Canada.
Smithsonian Tropical Research Institute, Balboa, Ancon, Panama, Panama.
PLoS One. 2014 May 15;9(5):e97593. doi: 10.1371/journal.pone.0097593. eCollection 2014.
Many species reproduce when conditions are most favorable for the survival of young. Numerous intertidal fish and invertebrates release eggs or larvae during semilunar, large amplitude, nocturnal tides when these early life stages are best able to escape predation by fish that feed near the shore during the day. Remarkably, some species, including the fiddler crabs Uca terpsichores and Uca deichmanni, maintain this timing throughout the year as temperature, and thus the rate of embryonic development, vary. The mechanisms that allow such precision in the timing of the production of young are poorly known. A preliminary study suggested that when temperature decreases, U. terpsichores mate earlier in the tidal amplitude cycle such that larvae are released at the appropriate time. We tested this idea by studying the timing of courtship in U. terpsichores and U. deichmanni as temperature varied annually during two years, at 5 locations that differed in the temperature of the sediment where females incubate their eggs. Uca terpsichores courted earlier at locations where sediment temperature declined seasonally but not where sediment temperature remained elevated throughout the year. In contrast, clear shifts in courtship timing were not observed for U. deichmanni despite variation in sediment temperature. We discuss other mechanisms by which this species may maintain reproductive timing. These two species are likely to be affected differently by changes in the frequency and intensity of cold periods that are expected to accompany climate change.
许多物种会在对幼体生存最为有利的条件下进行繁殖。众多潮间带鱼类和无脊椎动物会在半月一次的、大幅度的夜间潮汐期间释放卵子或幼体，因为在这些早期生命阶段，它们最能够躲避白天在岸边觅食的鱼类的捕食。值得注意的是，包括招潮蟹Uca terpsichores和Uca deichmanni在内的一些物种，全年都保持着这种时间规律，尽管温度会发生变化，胚胎发育速率也会随之改变。目前对于能够在幼体繁殖时间上实现如此精确性的机制，我们了解得还很少。一项初步研究表明，当温度下降时，U. terpsichores会在潮汐幅度周期中更早地进行交配，以便在合适的时间释放幼体。我们通过研究U. terpsichores和U. deichmanni在两年间随着每年温度变化的求偶时间，以及在五个雌性孵化卵子的沉积物温度不同的地点，来验证这一观点。在沉积物温度季节性下降的地点，Uca terpsichores会更早求偶，但在沉积物温度全年保持较高的地点则不会。相比之下，尽管沉积物温度有所变化，但未观察到U. deichmanni的求偶时间有明显变化。我们讨论了该物种可能维持繁殖时间的其他机制。预计气候变化将伴随寒冷期的频率和强度变化，这两个物种可能会受到不同的影响。
