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.

北美太平洋海岸的杜父鱼（Sculpin fishes）为探究适应性形态特征演化是否推动物种占领新生境类型提供了理想研究体系，因其系统发育与生态背景均已得到充分阐释。该类群中，基部起源的物种主要栖息于潮下带生境，而最衍生支系的物种则分布于潮间带。我们通过检验多种演化模型，以明确杜父鱼的体型大小与鳞片数量变化是否属于适应生境利用的适应性特征。基于涵盖26种杜父鱼的高分辨率、统计严谨的分子系统发育树，结合形态测量学与生境亲和性数据，本研究的分析结果显示，基于生境利用的适应性模型最能解释杜父鱼体型与鳞片数量的演化变化。相较于中性演化模型、所有生境下的稳定选择模型以及三种基于支系的模型，该生境模型获得了统计学支持。我们推测，潮间带物种的鳞片丢失与体型缩小，或可在退潮潮池缺氧时辅助皮肤呼吸。本研究展示了结合系统发育学、生态学与统计学研究方法，如何助力识别可能适应新生境的关键性状。