Conservation Biology Research Group, School of Environmental and Life Sciences, University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.
Centre for Conservation Ecology and Genomics, Institute for Applied Ecology, University of Canberra, Bruce, ACT, 2617, Australia.
Oecologia. 2022 Mar;198(3):699-710. doi: 10.1007/s00442-022-05139-2. Epub 2022 Mar 5.
Animals that reproduce in temporary aquatic systems expose their offspring to a heightened risk of desiccation, as they must race to complete development and escape before water levels recede. Adults must therefore synchronise reproduction with the changing availability of water, yet the conditions they experience to trigger such an event may not relate to those offspring face throughout development, potentially leading to clutch failure. The sandpaper frog (Lechriodus fletcheri) breeds in ephemeral pools that dry within days to weeks after rainfall has ceased. We examined whether spawning frequency and offspring survival differed across two consecutive breeding seasons based on (1) rainfall at the moment of oviposition and throughout offspring development, and (2) pool volume, given their combined effect on hydroperiod. Reproduction was triggered by rainfall, with more spawn laid during periods of greater rainfall and in larger pools. While pool size was a predictor of offspring survival, rainfall during oviposition was not. Rather, follow-up rain events were required to prevent pools drying prior to metamorphosis, with rainfall evenness during development the strongest predictor of reproductive success. High clutch failure rates recorded in both seasons suggest that adults do not have the capability to predict rainfall frequency post-oviposition. We thus conclude that unpredictable rainfall leading to premature desiccation of spawning sites is the primary source of pre-metamorphic mortality for this species. Understanding the influence of rainfall predictability on offspring survival could be critical in predicting the effects of altered hydroperiod regimes due to climate change for species that exploit temporary waters.
在临时水生系统中繁殖的动物将其后代暴露在更高的脱水风险中，因为它们必须在水位下降之前迅速完成发育并逃离。因此，成年动物必须使繁殖与水的变化可用性同步，但触发这种事件的条件可能与后代在整个发育过程中所面临的条件无关，这可能导致卵的孵化失败。砂纸蛙（Lechriodus fletcheri）在短暂的池塘中繁殖，这些池塘在降雨停止后几天到几周内就会干涸。我们研究了两次连续繁殖季节中产卵频率和后代存活率是否存在差异，这取决于（1）产卵时和后代发育过程中的降雨，以及（2）由于它们对水期的综合影响而导致的池塘体积。繁殖是由降雨触发的，在降雨量较大的时期和在较大的池塘中产卵更多。虽然池塘大小是后代存活率的预测因素，但产卵时的降雨量不是。相反，需要后续的降雨事件来防止池塘在变态前干涸，而在发育过程中降雨的均匀性是繁殖成功的最强预测因素。两个季节中都记录到高的卵孵化失败率表明，成年动物没有能力预测产卵后的降雨频率。因此，我们得出结论，导致产卵地点过早干涸的不可预测降雨是该物种在变态前死亡的主要原因。了解降雨可预测性对后代存活率的影响对于预测由于气候变化而导致的利用临时水域的物种的水期变化制度的影响可能至关重要。
