Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Biology Department, Williams College, Williamstown, Massachusetts, 01267.
Evolution. 2021 Jul;75(7):1862-1877. doi: 10.1111/evo.14282. Epub 2021 Jun 19.
We estimated natural selection targeting three traits related to habitat choice in a frog (Pseudacris maculata) breeding in pools on the rocky shores of Isle Royale, Michigan, over 16 years. Our aim was to identify the form and ecological causes of annual variation in directional and correlational selection as expressed in the survival and growth of tadpoles. We found directional selection favoring early breeding, but pool choice was under weak stabilizing selection. However, the form of stabilizing selection and the position of the optimum trait value shifted among years with the severity of disturbance and the intensity of biotic interactions. In years when wave wash and pool desiccation were severe, selection shifted to favor tadpoles in habitats where these risks were less pronounced. If predatory dragonfly larvae were abundant, selection favored tadpoles in small pools where dragonflies did not occur. When intraspecific competition was strong, selection favored early broods within a broader range of pool types. The agents of selection in this study-biotic interactions and disturbance-are common to many ecological systems and frequently exhibit temporal variation; this suggests that fluctuating selection may be widespread in natural populations.
我们在过去的 16 年中，评估了密歇根州皇家岛岩滩上池塘中繁殖的青蛙（Pseudacris maculata）的三个与栖息地选择相关的特征的自然选择。我们的目的是确定定向和相关选择在蝌蚪的生存和生长中的年度变化的形式和生态原因。我们发现了有利于早期繁殖的定向选择，但池塘选择受到较弱的稳定选择的影响。然而，稳定选择的形式和最优特征值的位置在干扰的严重程度和生物相互作用的强度之间的年份中发生了变化。在波蚀和池塘干燥严重的年份，选择有利于风险较小的栖息地中的蝌蚪。如果捕食性蜻蜓幼虫大量存在，选择就会倾向于没有蜻蜓的小池塘中的蝌蚪。当种内竞争强烈时，选择会在更广泛的池塘类型范围内优先选择早期的群体。本研究中的选择代理——生物相互作用和干扰——在许多生态系统中很常见，并且经常表现出时间变化；这表明波动选择可能在自然种群中广泛存在。
