Many paths to a common destination: morphological differentiation of a functionally convergent visual signal

Understanding the interacting outcomes of selection and historical contingency in shaping adaptive evolution remains a challenge in evolutionary biology. While selection can produce convergent outcomes when species occupy similar environments, the unique history of each species can also influence evolutionary trajectories and result in different phenotypic end points. The question is to what extent historical contingency places species on different adaptive pathways and, in turn, the extent to which we can predict evolutionary outcomes. Among lizards there are several distantly related genera that have independently evolved an elaborate extendible dewlap for territorial communication. We conducted a detailed morphological study and employed new phylogenetic comparative methods to investigate the evolution of the underlying hyoid that powers the extension of the dewlap. This analysis showed that there appear to have been multiple phenotypic pathways for evolving a functionally convergent...

探明自然选择与历史偶然性在塑造适应性进化过程中的交互效应，仍是进化生物学研究中的难点之一。尽管当物种栖息于相似环境时，自然选择可催生趋同演化结果，但每个物种独有的演化历史同样会影响其演化轨迹，进而产生各异的表型终点。核心问题在于：历史偶然性在多大程度上会将物种引向不同的适应性演化路径，而我们又能在多大程度上准确预测演化结果。在蜥蜴类群中，多个远缘属物种均独立演化出了结构复杂的可伸缩喉扇（extendible dewlap），用于领地通讯。本研究开展了细致的形态学分析，并运用新型系统发育比较方法（phylogenetic comparative methods），探究驱动喉扇伸缩的舌骨（hyoid）结构的演化历程。本分析结果显示，实现功能趋同的喉扇演化似乎存在多条表型路径……