Data from: Adaptive morphological shifts to novel habitats in marine sculpin fishes

Sculpin fishes of the North American Pacific Coast provide an ideal opportunity to examine whether adaptive morphological character shifts have facilitated occupation of novel habitat types because of their well-described phylogeny and ecology. In this group, the basal-rooted species primarily occupy the subtidal habitat, whereas the species in the most distal clades are found in the intertidal. We tested multiple evolutionary models to determine whether changes in body size and changes in number of scales are adaptive for habitat use in sculpins. Based on a statistically robust, highly resolved molecular phylogeny of 26 species of sculpins, in combination with morphometric and habitat affinity data, our analyses show that an adaptive model based on habitat use best explains changes in body size and number of scales. The habitat model was statistically supported over models of neutral evolution, stabilizing selection across all habitats, and three clade-based models. We suggest that loss of scales and reduction of body size in the intertidal may facilitate cutaneous breathing in air when tidepools become hypoxic during low tides. This study demonstrates how the combined use of phylogenetic, ecological and statistical approaches helps to identify traits that are likely adaptive to novel habitats.

北美太平洋沿岸的杜父鱼（sculpin）由于其系统发育与生态学背景均已得到充分阐释，为探究适应性形态特征演化是否推动物种开拓新型栖息环境提供了理想的研究模型。该类群中，基部分化类群的物种主要栖息于潮下带环境，而演化分支最末端的物种则多分布于潮间带。本研究针对杜父鱼展开多套演化模型检验，以明确体型变化与鳞片数量变化是否与其栖息环境的适应性演化相关。本研究基于涵盖26种杜父鱼的统计稳健、高分辨率分子系统发育树，并结合形态测量数据与栖息偏好数据展开分析，结果显示基于栖息环境的适应性模型能够最优解释杜父鱼的体型与鳞片数量变化。相较于中性演化模型、全栖息环境下的稳定选择模型以及3种基于演化分支的模型，该栖息环境适应性模型在统计检验中得到了显著支持。我们推测，潮间带物种的鳞片丢失与体型缩小，或有助于其在低潮期潮池出现低氧时进行空气皮肤呼吸。本研究证实了结合系统发育学、生态学与统计学方法，如何助力研究者甄别出与新型栖息环境适应性演化相关的形态特征。