Data from: The evolution of vertebrate eye size across an environmental gradient: phenotype does not predict genotype in a Trinidadian killifish

Vertebrates exhibit substantial variation in eye size. Eye size correlates positively with visual capacity and behaviors that enhance fitness, such as predator avoidance. This foreshadows a connection between predation and eye size evolution. Yet, the conditions that favor evolutionary shifts in eye size, besides the well-known role for light availability, are unclear. We tested the influence of predation on the evolution of eye size in Trinidadian killifish, Rivulus hartii. Rivulus are located across a series of communities where they coexist with visually oriented piscivores (‘high predation’ sites), and no predators (‘Rivulus-only’ sites). Wild-caught Rivulus from high predation sites generally exhibited a smaller relative eye size than communities that lack predators. Yet, such differences were inconsistent across rivers. Second-generation common garden reared fish revealed repeatable decreases in eye size in Rivulus from high predation sites. We performed additional experiments that tested the importance of light and resources on eye size evolution. Sites that differ in light or resource availability did not differ in eye size. Our results argue that differences in predator-induced mortality underlie genetically-based shifts in vertebrate eye size. We discuss the drivers of eye size evolution in light of the nonparallel trends between the phenotypic and common garden results.脊椎动物的眼球大小存在显著变异。眼球大小与视觉能力以及提升演化适应度的行为（如反捕食行为）呈正相关，这预示着捕食压力与眼球大小演化之间存在关联。然而，除了已被广泛认知的光照可利用性的作用外，哪些条件会推动眼球大小的演化改变，目前仍不明确。本研究以特立尼达底鳉（*Rivulus hartii*）为研究对象，探究了捕食压力对其眼球大小演化的影响。该物种分布于一系列群落中：要么与以视觉为导向的肉食性鱼类（piscivores）共存，对应“高捕食压力生境”；要么无任何捕食者存在，对应“仅存底鳉生境”。野外捕获的高捕食压力生境个体，其相对眼球大小通常低于无捕食者生境的个体，但这类差异在不同河流间并不一致。第二代共同花园实验（common garden）饲养的个体显示，高捕食压力生境来源的底鳉眼球大小呈现出可重复的降低趋势。我们还开展了额外实验，以探究光照与资源可利用性对眼球大小演化的影响。结果发现，光照或资源可利用性存在差异的生境，其底鳉的眼球大小并无显著差异。本研究结果表明，捕食压力引发的死亡率差异，是驱动脊椎动物眼球大小发生遗传基础改变的核心原因。最后，我们结合表型结果与共同花园实验结果之间的非平行趋势，探讨了眼球大小演化的驱动机制。