Ecology and Evolutionary Biology Department, Princeton University, Princeton NJ 08544;
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104.
Proc Natl Acad Sci U S A. 2021 Feb 9;118(6). doi: 10.1073/pnas.2015772118.
Eco-evolutionary dynamics will play a critical role in determining species' fates as climatic conditions change. Unfortunately, we have little understanding of how rapid evolutionary responses to climate play out when species are embedded in the competitive communities that they inhabit in nature. We tested the effects of rapid evolution in response to interspecific competition on subsequent ecological and evolutionary trajectories in a seasonally changing climate using a field-based evolution experiment with Populations of were either exposed, or not exposed, to interspecific competition with an invasive competitor, , over the summer. We then quantified these populations' ecological trajectories (abundances) and evolutionary trajectories (heritable phenotypic change) when exposed to a cooling fall climate. We found that competition with in the summer affected the subsequent evolutionary trajectory of populations in the fall, after all interspecific competition had ceased. Specifically, flies with a history of interspecific competition evolved under fall conditions to be larger and have lower cold fecundity and faster development than flies without a history of interspecific competition. Surprisingly, this divergent fall evolutionary trajectory occurred in the absence of any detectible effect of the summer competitive environment on phenotypic evolution over the summer or population dynamics in the fall. This study demonstrates that competitive interactions can leave a legacy that shapes evolutionary responses to climate even after competition has ceased, and more broadly, that evolution in response to one selective pressure can fundamentally alter evolution in response to subsequent agents of selection.
生态进化动力学将在确定物种命运方面发挥关键作用，因为气候条件正在发生变化。不幸的是，我们对物种在自然栖息地中竞争的群落中，对气候的快速进化反应如何发挥作用知之甚少。我们通过一个基于野外的进化实验检验了物种在快速进化以应对种间竞争后，在季节变化的气候中对随后的生态和进化轨迹的影响。在夏季，我们的种群要么暴露于与入侵竞争者的种间竞争，要么不暴露于这种竞争。然后，我们量化了这些种群在接触到秋季降温气候时的生态轨迹（丰度）和进化轨迹（可遗传的表型变化）。我们发现，夏季与竞争会影响秋季种群的后续进化轨迹，即使所有的种间竞争都已经停止。具体来说，有过种间竞争历史的苍蝇在秋季条件下进化为体型更大、耐寒性更低、发育速度更快，而没有种间竞争历史的苍蝇则没有。令人惊讶的是，这种夏季竞争环境对夏季表型进化或秋季种群动态没有任何可察觉影响的情况下，秋季的进化轨迹发生了分歧。本研究表明，即使竞争已经停止，竞争也可以留下影响进化对气候反应的遗产，更广泛地说，对一种选择压力的进化反应可以从根本上改变对随后选择因素的进化反应。
