Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, 50011.
Evolution. 2022 Jul;76(7):1607-1618. doi: 10.1111/evo.14541. Epub 2022 Jun 23.
Eyes are remarkable systems to investigate the complex interaction between ecological drivers and phenotypic outcomes. Some animals, such as scallops, have many eyes for visual perception, but to date, the evolution of multiple-eye systems remains obscure. For instance, it is unclear whether eye number changes over a lifetime or varies among species. Scallops are a suitable model group to investigate these questions considering the interspecific variation of adult size and ecological diversity. We tested whether eye abundance scales with body size among individuals and species and whether it varies with life habits. We performed comparative analyses, including a phylogenetic ANCOVA and evolutionary model comparisons, based on eye count and shell height (as a proxy of body size) across 31 scallop species. Our analyses reveal that patterns of increasing relationship with body size are not concordant among taxa and suggest ontogenetic convergence caused by similar ecologies. Accordingly, selective optima in eye numbers are associated with shifts in life habits. For instance, species with increased mobility have significantly more eyes than less mobile species. The convergent evolution of greater eye abundance in more mobile scallops likely indicates a visual improvement based on increased levels of oversampling of the surrounding environment.
眼睛是研究生态驱动因素和表型结果之间复杂相互作用的卓越系统。有些动物，如扇贝，有许多用于视觉感知的眼睛，但迄今为止，多眼系统的进化仍然不清楚。例如，眼睛数量是否会随着个体的一生而变化，或者是否会因物种而异，这些都不清楚。考虑到成年体型和生态多样性的种间变化，扇贝是一个适合用来研究这些问题的模型群体。我们测试了个体和物种之间的眼睛数量是否与体型成正比，以及它是否随生活习性而变化。我们进行了比较分析，包括基于 31 种扇贝的眼睛数量和壳高（作为体型的替代物）的系统发育方差分析和进化模型比较。我们的分析表明，与体型呈正相关的模式在分类群中并不一致，并表明由相似生态引起的个体发育趋同。因此，眼睛数量的选择最优与生活习性的变化有关。例如，移动性更强的物种比移动性较弱的物种有更多的眼睛。在更具移动性的扇贝中，眼睛数量的趋同进化可能表明，基于对周围环境的过度抽样水平的提高，视觉得到了改善。
