The order Characiformes is one of the most diverse and widely distributed groups of fishes in cis-Andean basins. That diversity is reflected in the São Francisco River (Brazil), where approximately 1/3 of all described species belong to that order, with many being endemic and/or considered endangered. The great morphological diversity observed in this group has been the focus of several systematic, ecomorphological, and evolutionary studies. Here, we evaluated the morphological patterns of 39 species of Characiformes from the São Francisco River using geometric morphometric and comparative phylogenetic techniques to better understand how ecological factors can modulate morphological diversity. Our data produced a highly supported topology revealing two promoters that drive the diversity of the analyzed forms, one is associated with phylogenetic inheritance, while the other is modulated by habitat, generating similarities between phylogenetically distant species. The absence of any observed relationship between body shape and trophic niche may reflect phylogenetic inertia of food preferences and morphological characteristics. Our data highlights the importance of combined analysis of all available evidences for understanding the evolutionary routes of diverse groups, as is the case of the Characiformes of the São Francisco River.

Characiformes 目是顺安第斯盆地中最多样化和分布最广的鱼类群之一。这种多样性反映在圣弗朗西斯科河（巴西），那里大约 1/3 的被描述物种属于该目，其中许多是地方性的和/或被认为是濒危物种。在这个群体中观察到的巨大形态多样性一直是几项系统、生态形态和进化研究的重点。在这里，我们使用几何形态测量和比较系统发育技术评估了来自圣弗朗西斯科河的 39 种 Characiformes 的形态模式，以更好地了解生态因素如何调节形态多样性。我们的数据产生了一个高度支持的拓扑结构，揭示了两个推动分析形式多样性的启动子，一种与系统发育遗传有关，而另一种则受栖息地调节，从而在系统发育上相距遥远的物种之间产生相似性。体型和营养生态位之间没有任何观察到的关系可能反映了食物偏好和形态特征的系统发育惰性。我们的数据强调了对所有可用证据进行综合分析以了解不同群体的进化路线的重要性，例如圣弗朗西斯科河的 Characiformes。