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.

本研究利用几何形态测量法（geometric morphometrics），对隶属于南美豚鼠型啮齿类三个总科（豚鼠总科Cavioidea、毛丝鼠总科Chinchilloidea以及八齿鼠总科Octodontoidea）的17个属的下颌骨形态变异情况展开分析。本研究通过系统发育比较法（phylogenetic comparative methods），评估了系统发育与生态因素对该形态变异的相对影响程度。绝大多数形态变异集中于髁突（condylar process）、冠突（coronoid process）、角突（angular process）以及齿隙（diastema）区域。仅八齿鼠总科类群具备潜在利于掘土的形态特征（即高冠突与高髁突、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，这或代表其掘土习性受到结构层面的制约。毛丝鼠总科类群表现出介于两者之间的形态特征。各属在形态空间（morphospace）中的分布与其所属总科分支的分类结果相一致。形态组分的系统发育信号（phylogenetic signal）在系统发育路径上呈现显著相关性，而在考虑系统发育结构的前提下，下颌骨形态与生态因素之间的关联并不显著。主要豚鼠型啮齿类分支间下颌骨形态的早期演化分化，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。