Artificial selection on reproductive timing in hatchery salmon drives a phenological shift and potential maladaptation to climate change

The timing of breeding migration and reproduction links generations and substantially influences individual fitness. In salmonid fishes, such phenological events (seasonal return to fresh water and spawning) vary among populations but are consistent among years, indicating local adaptation in these traits to prevailing environmental conditions. Changing reproductive phenology has been observed in many populations of salmonids, and is sometimes attributed to adaptive responses to climate change. The sockeye salmon spawning in the Cedar River near Seattle, Washington have displayed dramatic changes in spawning timing over the past 50 years, trending later through the early 1990s, and becoming earlier since then. We explored the patterns and drivers of these changes using generalized linear models and mathematical simulations to identify possible environmental correlates of the changes, and test the alternative hypothesis that hatchery propagation caused inadvertent selection on timing. Th...繁殖迁徙与繁殖活动的时序维系了世代间的联系，并对个体适合度（individual fitness）产生显著影响。对于鲑科鱼类（salmonid fishes）而言，这类物候事件（phenological events，即季节性洄游至淡水并产卵）在不同种群间存在差异，但年际间保持稳定，表明这些性状针对当地环境条件存在本地适应。目前已在多个鲑科鱼类种群中观测到繁殖物候的改变，此类变化有时被归因于对气候变化的适应性响应。栖息于华盛顿州西雅图附近锡达河（Cedar River）的红大马哈鱼（sockeye salmon），在过去50年间其产卵时序发生了显著变化：1990年代早期前产卵时间持续延后，此后则逐渐提前。本研究采用广义线性模型（generalized linear models）与数学模拟方法，探究了此类变化的模式与驱动因素，以识别可能与该变化相关的环境因子，并验证“孵化场繁育放流（hatchery propagation）对产卵时序产生了无意的选择压力”这一备择假设。（原文未完结）