Adaptation to herbivory and detritivory drives the convergent evolution of large abdominal cavities in a diverse freshwater fish radiation (Otophysi: Characiformes)

Convergent evolution is often interpreted as evidence of natural selection favoring an optimal phenotype during adaptation. Morphological convergence is frequently found among lineages that converge on diet, but most studies have focused on morphological traits that relate exclusively to food handling and processing. In vertebrates, there is a strong inverse relationship between intestine length and trophic level.  However, little is known about whether adaptation to a low trophic level influences the evolution of abdominal cavities that can accommodate larger intestines. Here, I reconstruct the evolutionary history of trophic ecology and examine abdominal cavity shape across 157 species of the fish order Characiformes to determine whether adaptation to an herbivorous-detritivorous diet drives convergent evolution of large abdominal cavities. Herbivorous-detritivorous species evolved significantly larger abdominal cavities than other trophic groups and repeatedly converged on a similar ...

趋同进化（Convergent evolution）常被解读为自然选择在适应过程中偏好最优表型（phenotype）的证据。形态趋同常见于饮食趋同的谱系中，但多数研究聚焦于仅与食物处理和加工相关的形态特征。在脊椎动物中，肠道长度与营养级（trophic level）之间存在强烈的逆相关关系。然而，关于适应低营养级是否会影响能容纳更长肠道的腹腔（abdominal cavity）的进化，目前知之甚少。在此，我重构了营养生态学（trophic ecology）的进化历史，并分析了脂鲤目（Characiformes）157个物种的腹腔形态，以确定适应植食性-碎屑食性（herbivorous-detritivorous）饮食是否会推动大腹腔的趋同进化。