Evolutionary constraints may significantly bias phenotypic change, while “breaking” from such constraints can lead to expanded ecological opportunity. Ray-finned fishes have broken functional constraints by developing two jaws (oral-pharyngeal), decoupling prey capture (oral jaw) from processing (pharyngeal jaw). It is hypothesized that the oral and pharyngeal jaws represent independent evolutionary modules and this facilitated diversification in feeding architectures. Here we test this hypothesis in African cichlids. Contrary to our expectation, we find integration between jaws at multiple evolutionary levels. Next, we document integration at the genetic level, and identify a candidate gene, smad7, within a pleiotropic locus for oral and pharyngeal jaw shape that exhibits correlated expression between the two tissues. Collectively, our data show that African cichlid evolutionary success has occurred within the context of a coupled jaw system, an attribute that may be driving adaptive evolution in this iconic group by facilitating rapid shifts between foraging habitats, providing an advantage in a stochastic environment such as the East African Rift-Valley.

进化限制可能会显着影响表型变化，而“打破”这些限制可能会导致生态机会的扩大。射线鳍鱼通过发育两个颌（口咽），将猎物捕获（口颌）与处理（咽颌）分离，从而打破了功能限制。据推测，口腔和咽颌代表独立的进化模块，这促进了进食结构的多样化。在这里，我们在非洲慈鲷中检验了这一假设。与我们的预期相反，我们发现颌骨在多个进化层面上存在整合。接下来，我们在基因水平上记录整合，并在口腔和咽颌形状的多效性基因座内鉴定出候选基因smad7 ，该基因在两种组织之间表现出相关表达。总的来说，我们的数据表明，非洲丽鱼科鱼的进化成功是在耦合下颌系统的背景下发生的，这一属性可能通过促进觅食栖息地之间的快速转变来推动这一标志性群体的适应性进化，从而在随机环境中提供优势，例如东非大裂谷。