Pinceel Tom, Vanschoenwinkel Bram, Hawinkel Wouter, Tuytens Karen, Brendonck Luc
Laboratory of Aquatic Ecology, Evolution and Conservation, KU Leuven, Charles Deberiotstraat 32, 3000, Louvain, Belgium.
Centre for Environmental Management, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa.
Oecologia. 2017 May;184(1):161-170. doi: 10.1007/s00442-017-3858-8. Epub 2017 Mar 24.
Climate change does affect not only average rainfall and temperature but also their variation, which can reduce the predictability of suitable conditions for growth and reproduction. This situation is problematic for inhabitants of temporary waters whose reproductive success depends on rainfall and evaporation that determine the length of the aquatic phase. For organisms with long-lived dormant life stages, bet hedging models suggest that a fraction of these should stay dormant during each growing season to buffer against the probability of total reproductive failure in variable environments. Thus far, however, little empirical evidence supports this prediction in aquatic organisms. We study geographic variation in delayed hatching of dormant eggs in natural populations of two crustaceans, Branchinella longirostris and Paralimnadia badia, that occur in temporary rock pools along a 725 km latitudinal aridity gradient in Western Australia. Consistent with bet hedging theory, populations of both species were characterised by delayed hatching under common garden conditions and hatching fractions decreased towards the drier end of the gradient where the probability of reproductive success was shown to be lower. This decrease was most pronounced in the species with the longer maturation time, presumably because it is more sensitive to the higher prevalence of short inundations. Overall, these findings illustrate that regional variation in climate can be reflected in differential investment in bet hedging and hints at a higher importance of delayed hatching to persist when the climate becomes harsher. Such strategies could become exceedingly relevant as determinants of vulnerability under climate change.
气候变化不仅会影响平均降雨量和温度，还会影响它们的变化，这可能会降低生长和繁殖适宜条件的可预测性。这种情况对于临时水域的生物来说是个问题，它们的繁殖成功取决于决定水生阶段长度的降雨和蒸发。对于具有长寿休眠生命阶段的生物，风险对冲模型表明，其中一部分应该在每个生长季节保持休眠，以缓冲在多变环境中完全繁殖失败的可能性。然而，到目前为止，很少有实证证据支持水生生物的这一预测。我们研究了两种甲壳类动物——长吻鳃足虫（Branchinella longirostris）和巴氏副仙女虾（Paralimnadia badia）自然种群中休眠卵延迟孵化的地理变异，它们出现在西澳大利亚沿725公里纬度干旱梯度的临时岩石池中。与风险对冲理论一致，在共同培养条件下，这两个物种的种群都表现出延迟孵化的特征，并且孵化率朝着梯度较干燥的一端下降，在那里繁殖成功的概率较低。这种下降在成熟时间较长的物种中最为明显，大概是因为它对短期洪水的较高发生率更敏感。总体而言，这些发现表明，气候的区域差异可以反映在风险对冲的不同投资上，并暗示当气候变得更恶劣时，延迟孵化对于生存的重要性更高。作为气候变化下脆弱性的决定因素，这些策略可能会变得极其重要。
