Rates of speciation and morphological evolution are correlated across the largest vertebrate radiation

Several evolutionary theories predict that rates of morphological change should be positively associated with the rate at which new species arise. For example, the theory of punctuated equilibrium proposes that phenotypic change typically occurs in rapid bursts associated with speciation events. However, recent phylogenetic studies have found little evidence linking these processes in nature. Here we demonstrate that rates of species diversification are highly correlated with the rate of body size evolution across the 30,000+ living species of ray-finned fish that comprise the majority of vertebrate biological diversity. This coupling is a general feature of fish evolution and transcends vast differences in ecology and body-plan organization. Our results may reflect a widespread speciational mode of character change in living fishes. Alternatively, these findings are consistent with the hypothesis that phenotypic ‘evolvability’ – the capacity of organisms to evolve – shapes the dynamics...

多项演化理论均预言，形态演化速率应与新物种形成速率呈正相关。例如，间断平衡论（punctuated equilibrium）提出，表型变化通常以快速爆发的形式发生，且与物种形成事件紧密关联。然而，近期的系统发育研究几乎未在自然界中发现这两类过程存在关联的证据。本研究针对占脊椎动物生物多样性绝大多数的3万余种现生辐鳍鱼类（ray-finned fish），证实物种多样化速率与体型大小演化速率高度相关。这种耦合关系是鱼类演化的普遍特征，跨越了生态与躯体构型的巨大差异。我们的研究结果或可反映现生鱼类中一类广泛存在的、与物种形成相关的性状演化模式。此外，这些发现与“表型可演化性（evolvability）——即生物体的演化能力——塑造演化动态……”这一假说相符。