对表型进化的限制可以导致趋同进化的模式,通过限制面对内源性(功能性,发展)或外生(竞争,捕食)选择性压力。对收敛性的评估取决于将生态和形态数据整合到一个稳健的、比较系统发育背景。硬骨鱼的惊人多样性提供了许多适应类似生态角色的谱系,因此,提供了许多重复的进化实验来探索表型趋同。然而,我们对鱼类喂养系统的理解主要是由海洋物种形成的,除了淡水丽鱼科鱼。在这里,我们使用食人鱼和pacus(Serrasalmidae)来探索新热带淡水环境中不同摄食生态及其形态代理的演变。具体来说,我们探讨了以植物为食的鱼类之间的融合是否更为普遍,源于对食草动物表型进化的强烈限制。使用骨学显微计算机断层扫描成像(μCT),我们描述了pacus和piranhas的形态变异的主轴,关于他们的饮食和喂养行为。接下来,我们评估了草食性生态位是否比其他饮食行会更不稳定,以及草食性物种的表型是否比其他分类群进化速度更慢。然后,我们评估草食类群的趋同程度,使用三种不同的形态特征套件(牙齿,下巴,和腹部形态计量学)。生态学上,食草动物不是死胡同,表现出与食肉动物和杂食动物之间相似的观察到的过渡率。然而,我们记录了食草动物的广泛趋同,食草动物的表型进化速度比食肉动物慢。大多数趋同的例子都是在食草类群中发现的,特别是在食肉动物和树叶中。此外,\'完全\'收敛的实例,在多个形态测量数据集中观察到的正收敛度量表明,只在食草动物中发现。食草动物似乎在受限的情况下进化,但这并没有限制他们的生态不稳定。
Constraints on phenotypic evolution can lead to patterns of convergent evolution, by limiting the \'pool\' of potential phenotypes in the face of endogenous (functional, developmental) or exogenous (competition, predation) selective pressures. Evaluation of convergence depends on integrating ecological and morphological data within a robust, comparative phylogenetic context. The staggering diversity of teleost fishes offers a multitude of lineages adapted for similar ecological roles, and therefore, offers numerous replicated evolutionary experiments for exploring phenotypic convergence. However, our understanding of fish feeding systems has been primarily shaped by marine species, with the monolithic exception of freshwater cichlids. Here we use piranhas and pacus (Serrasalmidae) to explore the evolution of different feeding ecologies and their morphological proxies in Neotropical freshwater environments. Specifically, we explore whether convergence is more widespread among plant-eating fishes, arising from strong constraints on phenotypic evolution in herbivores. Using osteological micro-computed tomographic imaging (μCT), we describe the major axes of morphological variation in pacus and piranhas, regarding their diet and feeding behaviors. Next, we evaluated whether herbivorous niches are less labile than other dietary guilds and whether herbivorous species\' phenotypes evolve at a slower evolutionary rate than other taxa. We then assess how convergent herbivorous taxa are, using three different suites of morphological characters (dental, jaw, and abdominal morphometrics). Ecologically, herbivory is not a dead end, exhibiting similar observed transition rates as those between carnivores and omnivores. However, we documented widespread convergence in herbivores and that herbivores have slower rates of phenotypic evolution than carnivores. Most instances of convergence are found in herbivorous taxa, specifically in frugivores and folivores. Moreover, instances of \'complete\' convergence, indicated by positive convergence metrics observed in more than one morphometric dataset, were only found in herbivores. Herbivores do appear to evolve under constrained circumstances, but this has not limited their ecological lability.