Data from: Trophic specialisation drives morphological evolution in sea snakes

Viviparous sea snakes are the most rapidly speciating reptiles known, yet the ecological factors underlying this radiation are poorly understood. Here, we reconstructed dated trees for 75% of sea snake species and quantified body shape (forebody relative to hindbody girth), maximum body length and trophic diversity to examine how dietary specialisation has influenced morphological diversification in this rapid radiation. We show that sea snake body shape and size are strongly correlated with the proportion of burrowing prey in the diet. Specialist predators of burrowing eels have convergently evolved a ‘microcephalic’ morphotype with dramatically reduced forebody relative to hindbody girth and intermediate body length. By comparison, snakes that predominantly feed on gobies are generally short-bodied and small headed, but there is no evidence of convergent evolution. The eel specialists also exhibit faster rates of size and shape evolution compared to all other sea snakes, including those that feed on burrowing gobies. Our results suggest that trophic specialisation to particular burrowing prey (eels) has invoked strong selective pressures that manifest as predictable and rapid morphological changes. Further studies are needed to examine the genetic and developmental mechanisms underlying these dramatic morphological changes and assess their role in sea snake speciation.卵胎生海蛇（Viviparous sea snakes）是目前已知物种形成速率最快的爬行动物类群，但该类群适应性辐射背后的生态驱动因子仍未被充分阐释。本研究针对75%的海蛇物种构建了定年演化树（dated trees），并量化分析了体型（前躯干围度相对于后躯干围度）、最大体长与营养生态位多样性，以此探究食性特化如何影响这一快速辐射类群的形态多样化进程。研究结果表明，海蛇的体型与体长与其食谱中穴居猎物的占比显著相关。专食穴居鳗类的捕食者类群趋同演化出“小头型”（microcephalic morphotype）形态：其前躯干围度相较后躯干围度显著缩减，且体长处于中等水平。与之形成对比的是，主要以虾虎鱼（gobies）为食的海蛇类群通常躯干较短、头部偏小，但未发现存在趋同演化的证据。相较于其余所有海蛇类群（包括以穴居虾虎鱼为食的类群），穴居鳗类专食者的体型与形态演化速率更快。本研究结果显示，针对特定穴居猎物（鳗类）的食性特化施加了强烈的选择压力，进而催生了可预测且快速的形态演化改变。未来仍需开展进一步研究，以阐明这些显著形态改变背后的遗传与发育机制，并评估其在海蛇物种形成过程中所扮演的角色。