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.

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，但其辐射演化背后的生态驱动因子仍未被充分阐明。本研究针对75%的海蛇物种构建了时间校准的系统发育树（dated trees），并量化了躯干前部与后部围度之比、最大体长及营养生态位多样性（trophic diversity），以此探究食性特化（dietary specialisation）对该快速辐射类群形态多样化（morphological diversification）进程的影响。研究结果显示，海蛇的体型与躯干比例与食谱中穴居猎物（burrowing prey）的占比显著相关。以穴居鳗类为专食性猎物的类群，趋同演化出了“小头型（microcephalic）”形态型：其躯干前部围度相较后部显著缩减，且体长处于中等水平。相较之下，以虾虎鱼（gobies）为主要猎物的海蛇通常躯干较短、头部偏小，但未发现趋同演化的证据。专食鳗类的海蛇类群，其体型与形态的演化速率也快于其他所有海蛇，包括以穴居虾虎鱼为食的类群。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烈的选择压力，最终催生了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所发挥的作用。