Tingle J L, Gartner G E A, Jayne B C, Garland T
Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA, USA.
Department of Biological Sciences, ML006, University of Cincinnati, Cincinnati, OH, USA.
J Evol Biol. 2017 Nov;30(11):2031-2043. doi: 10.1111/jeb.13173. Epub 2017 Sep 21.
Understanding the origin and maintenance of functionally important subordinate traits is a major goal of evolutionary physiologists and ecomorphologists. Within the confines of a limbless body plan, snakes are diverse in terms of body size and ecology, but we know little about the functional traits that underlie this diversity. We used a phylogenetically diverse group of 131 snake species to examine associations between habitat use, sidewinding locomotion and constriction behaviour with the number of body vertebrae spanned by a single segment of the spinalis muscle, with total numbers of body vertebrae used as a covariate in statistical analyses. We compared models with combinations of these predictors to determine which best fit the data among all species and for the advanced snakes only (N = 114). We used both ordinary least-squares models and phylogenetic models in which the residuals were modelled as evolving by the Ornstein-Uhlenbeck process. Snakes with greater numbers of vertebrae tended to have spinalis muscles that spanned more vertebrae. Habitat effects dominated models for analyses of all species and advanced snakes only, with the spinalis length spanning more vertebrae in arboreal species and fewer vertebrae in aquatic and burrowing species. Sidewinding specialists had shorter muscle lengths than nonspecialists. The relationship between prey constriction and spinalis length was less clear. Differences among clades were also strong when considering all species, but not for advanced snakes alone. Overall, these results suggest that muscle morphology may have played a key role in the adaptive radiation of snakes.
理解功能重要的从属性状的起源和维持是进化生理学家和生态形态学家的主要目标。在无肢身体结构的范围内，蛇在体型和生态方面具有多样性，但我们对这种多样性背后的功能性状知之甚少。我们使用了131种系统发育多样的蛇类，来研究栖息地利用、侧行运动和绞杀行为与脊肌单个节段所跨越的椎体数量之间的关联，并将椎体总数作为统计分析中的协变量。我们比较了包含这些预测变量组合的模型，以确定在所有物种以及仅针对高等蛇类（N = 114）中，哪个模型最符合数据。我们同时使用了普通最小二乘模型和系统发育模型，其中残差被建模为通过奥恩斯坦-乌伦贝克过程进化。椎体数量较多的蛇往往具有跨越更多椎体的脊肌。栖息地效应在所有物种和仅高等蛇类的分析模型中占主导地位，树栖物种的脊肌长度跨越更多椎体，而水生和穴居物种的则较少。侧行专家的肌肉长度比非专家短。猎物绞杀与脊肌长度之间的关系不太明确。在考虑所有物种时，各分支之间的差异也很明显，但仅针对高等蛇类时并非如此。总体而言，这些结果表明肌肉形态可能在蛇类的适应性辐射中发挥了关键作用。
