DISSERTATION RESEARCH: The Ecomorphology of Arboreal Squirrels and the Evolution of Gliding Locomotion

研究人员检查运动的进化差异特征依赖于一个模型，即最初的行为改变随后是次要的形态变化。然而，对青蛙滑翔表现的研究表明，可能需要形态学和行为的伴随变化，这使得行为优先模型站不住脚。树栖松鼠提供了一个完美的系统来测试这个模型，因为从跳跃到滑翔的过渡可能发生在这个群体中。本研究的目的是确定从跳跃到滑翔的进化变化顺序是否符合行为优先模型。该研究检查了三种树栖松鼠（飞鼠、树松鼠、花栗鼠）和一种树栖近亲（睡鼠）在以下水平上的变异：1)形态学；2)生物力学;3)运动行为；4)生态。综合阶段采用多变量统计来总结这些水平的变化，并确定物种之间的显著性状差异。性状随后被映射到系统发育，以测试行为优先权。除了对该模型进行测试外，该研究还首次对灵长类动物以外的哺乳动物的树上跳跃进行了比较研究，并对哺乳动物的滑翔进行了唯一的详细描述。跳跃和滑翔运动的生物力学描述可能对那些打算在工程设计中使用动物作为模型系统的人有重要的意义。

Researchers examining evolutionary divergence in locomotion characteristically rely upon a model of initial behavioral modification followed by secondary morphological change. Yet, studies of gliding performance in frogs suggest that concomitant changes in morphology and behavior may be required, making the behavioral precedence model untenable. Arboreal squirrels provide a perfect system to test the model since a transition from leaping to gliding likely occurred in this group. The objective of the proposed study is to determine whether the sequence of evolutionary changes from leaping to gliding is consistent with the behavioral precedence model. The study examines variation in three arboreal squirrels (flying squirrel, tree squirrel, chipmunk) and a close arboreal relative (dormouse) at the following levels: 1) Morphology; 2) Biomechanics; 3) Locomotor behavior; and 4) Ecology. The synthesis phase employs multivariate statistics to summarize variation in these levels and to identify significant trait differences among species. Traits are subsequently mapped onto the phylogeny to test behavioral precedence. In addition to testing the model, the study provides the first comparative examination of mammalian arboreal leaping outside of primates, and the only detailed description of mammalian gliding. Biomechanical descriptions of leaping and gliding locomotion may have important implications for those intending to use animals as model systems in engineering design.