Divergent natural selection promotes immigrant inviability at early and late stages of evolutionary divergence

Natural selection's role in speciation has been of fundamental importance since Darwin first outlined his theory. Recently, work has focused on understanding how selection drives trait divergence, and subsequently reproductive isolation. ‘Immigrant inviability’, a barrier that arises from selection against immigrants in their non-native environment, appears to be of particular importance. Although immigrant inviability is likely ubiquitous, we know relatively little about how selection acts on traits to drive immigrant inviability, and how important immigrant inviability is at early-versus-late stages of divergence. We present a study evaluating the role of predation in the evolution of immigrant inviability in recently-diverged population pairs and a well-established species pair of Brachyrhaphis fishes. We evaluate performance in a high-predation environment by assessing survival in the presence of a predator, and swimming endurance in a low-predation environment. We find strong signa...

自达尔文首次系统阐述进化论以来，自然选择在物种形成过程中的作用始终是核心研究议题。近年来，相关研究聚焦于解析自然选择如何推动性状分化，进而促成生殖隔离。“移民不可存活（Immigrant inviability）”是指外来个体在非原生环境中因选择压力无法存活的生殖隔离障碍，该机制被认为具有尤为关键的作用。尽管移民不可存活现象可能广泛存在，但目前学界对自然选择如何作用于性状以催生该障碍，以及该障碍在物种分化的早期与后期阶段中的相对重要性仍知之甚少。本研究针对近期分化的种群对以及分化成熟的短颌脂鲤属（Brachyrhaphis）鱼类物种对，探究捕食压力在移民不可存活性状演化中的作用。我们通过检测捕食者存在时的存活率，评估高捕食压力环境下的生存表现；同时在低捕食压力环境中测定游泳耐力。我们发现显著的……