Data from: Ecological and phylogenetic influence on mandible shape variation of South American caviomorph rodents (Rodentia: Hystricomorpha)

We analyzed mandible shape variation of 17 genera belonging to three superfamilies (Cavioidea, Chinchilloidea and Octodontoidea) of South American caviomorph rodents using geometric morphometrics. The relative influence of phylogeny and ecology on this variation was assessed through phylogenetic comparative methods. Most morphological variation was concentrated in condylar, coronoid and angular processes, and the diastema. Features potentially advantageous for digging (i.e. high coronoid and condylar processes, relatively short angular process and diastema) were present only in octodontoids; cavioids showed opposite trends, which could represent a structural constraint for fossorial habits. Chinchilloids showed intermediate features. Genera distributed in the morphospace according to their classification into superfamilial clades. Phylogenetic signal for shape components was significant along phylogeny, while the relationship between mandibular shape and ecology was non significant when phylogenetic structure was taken into account. An early evolutionary divergence in the mandible shape among major caviomorph clades would explain the observed strong phylogenetic influence on the variation of this structure.

本研究采用几何形态测量学（geometric morphometrics）方法，对隶属于南美豚形亚目啮齿类3个总科（豚鼠总科Cavioidea、绒鼠总科Chinchilloidea与八齿鼠总科Octodontoidea）的17个属的下颌骨形态变异展开分析。通过系统发育比较法，评估了系统发育与生态学因素对该形态变异的相对影响程度。大部分形态变异集中于髁突、冠突、角突及齿隙区域。仅八齿鼠总科类群具备潜在的掘土适应性形态特征，即高冠突与髁突、相对较短的角突与齿隙；豚鼠总科类群则呈现相反的形态趋势，这可能代表了掘土习性所带来的结构约束。绒鼠总科类群的形态特征处于二者之间。各属在形态空间中的分布与其所属总科演化支的分类结果高度吻合。下颌骨形态组分的系统发育信号在系统发育树上呈现显著相关性；而在纳入系统发育结构进行校正后，下颌骨形态与生态学因素之间的关联并不显著。南美豚形亚目主要演化支间下颌骨形态的早期演化分化，或可解释本研究观测到的系统发育因素对该结构变异的强烈影响。