Adaptation in temporally variable environments: stickleback armor in periodically breaching bar-built estuaries

The evolutionary consequences of temporal variation in selection remain hotly debated. We explored these consequences by studying threespine stickleback in a set of bar-built estuaries along the central California coast. In most years, heavy rains induce water flow strong enough to break through isolating sand bars, connecting streams to the ocean. New sand bars typically re-form within a few weeks or months, thereby re-isolating populations within the estuaries. These breaching events cause severe and often extremely rapid changes in abiotic and biotic conditions, including shifts in predator abundance. We investigated whether this strong temporal environmental variation can maintain within-population variation while eroding adaptive divergence among populations that would be caused by spatial variation in selection. We used neutral genetic markers to explore population structure, and then analyzed how stickleback armor traits, the associated genes Eda and Pitx1, and elemental composi...

选择的时间变异所产生的进化后果仍备受争议。我们通过研究加州中部海岸一系列沙坝型河口内的三刺鱼（threespine stickleback），探讨了这些后果。多数年份中，暴雨引发的水流强度足以冲垮隔离沙坝，使溪流与海洋连通。新沙坝通常在数周或数月内重新形成，从而重新隔离河口内的种群。这些溃坝事件会导致非生物与生物环境条件发生剧烈且往往极其迅速的变化，包括捕食者丰度的改变。我们探究了这种强烈的时间环境变异是否能在维持种群内变异的同时，削弱由选择的空间变异所导致的种群间适应性分化。我们利用中性遗传标记分析种群结构，随后研究了三刺鱼的骨板性状、相关基因Eda与Pitx1，以及元素组成（elemental composi...）