Explosive bouts of diversification are one of the most conspicuous features of the tree of life. When such bursts are repeated in similar environments it suggests some degree of predictability in the evolutionary process. We assess parallel adaptive radiation of South American pike cichlids (Crenicichla) using phylogenomics and phylogenetic comparative methods. We find that species flocks in the Uruguay and Iguazú River basins rapidly diversified into the same set of ecomorphs that reflect feeding ecology. Both adaptive radiations involve expansion of functional morphology, resulting in unique jaw phenotypes. Yet, form and function were decoupled such that most ecomorphs share similar mechanical properties of the jaws (i.e., jaw motion during a feeding strike). Prey mobility explained six to nine-fold differences in the rate of morphological evolution, but had no effect on the rate of mechanical evolution. We find no evidence of gene flow between species flocks or with surrounding coastal lineages that may explain their rapid diversification. When compared to cichlids of the East African Great Lakes and other prominent adaptive radiations, pike cichlids share many themes, including rapid expansion of phenotypic diversity, specialization along the benthic-to-pelagic habitat and soft-to-hard prey axes, and the evolution of conspicuous functional innovations. Yet, decoupled evolution of form and function and the absence of hybridization as a catalyzing force are departures from patterns observed in other adaptive radiations. Many-to-one mapping of morphology to mechanical properties is a mechanism by which pike cichlids exhibit a diversity of feeding ecologies while avoiding exacerbating underlying mechanical trade-offs.

中文翻译：

---

南美派克慈鲷 (Crenicichla) 的快速平行形态和机械多样化

多元化的爆炸性发作是生命之树最显着的特征之一。当这种爆发在相似的环境中重复出现时，它表明进化过程中存在一定程度的可预测性。我们使用系统发育学和系统发育比较方法评估南美派克慈鲷 (Crenicichla) 的平行适应性辐射。我们发现乌拉圭和伊瓜苏河流域的物种群迅速多样化为反映摄食生态学的同一组生态形态。两种适应性辐射都涉及功能形态的扩展，从而产生独特的颌骨表型。然而，形式和功能是分离的，因此大多数 ecomorphs 具有相似的颌骨机械特性（即，进食期间的颌骨运动）。猎物的流动性解释了形态进化速率的六到九倍差异，但对机械进化速率没有影响。我们没有发现物种群之间或与周围沿海谱系之间的基因流动的证据可以解释它们的快速多样化。与东非五大湖的慈鲷和其他显着的适应性辐射相比，梭子鱼有许多共同点，包括表型多样性的快速扩展、沿底栖到远洋栖息地的专业化以及从软到硬的猎物轴，以及进化显着的功能创新。然而，形式和功能的分离进化以及杂交作为催化力的缺失与在其他适应性辐射中观察到的模式背道而驰。