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.卵胎生海蛇是目前已知物种形成速率最快的爬行动物类群，但其适应辐射背后的生态驱动因子仍未得到充分阐释。本研究针对75%的海蛇物种重建了定年系统发育树（dated trees），并量化了躯干形态（躯干前部与后部的周长比值）、最大体长及营养生态位多样性（trophic diversity），以此探究食性特化对这一快速辐射类群形态分化的影响。研究结果显示，海蛇的躯干形态与体型大小，与其食谱中穴居猎物的占比显著相关。以穴居鳗类为专食性猎物的类群，已趋同演化出小头型（microcephalic）形态：其躯干前部与后部的周长比显著降低，且体长处于中等水平。相较而言，主要以虾虎鱼（gobies）为食的海蛇通常躯干较短、头部偏小，但未发现趋同演化的证据。与所有其他海蛇类群（包括以穴居虾虎鱼为食的类群）相比，鳗类专食者的体型与形态演化速率也更快。本研究结果表明，针对特定穴居猎物（鳗类）的食性特化，施加了强劲的选择压力，最终表现为可预测且快速的形态变化。未来仍需开展进一步研究，以阐明这些显著形态变化背后的遗传与发育机制，并评估其在海蛇物种形成过程中发挥的作用。