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Free keywords:
adaptation, allometry, morphology, Ornstein–Uhlenbeck model, phylogenetic inertia, shape
Abstract:
Sciuromorph rodents are a monophyletic group comprising ~300 species that display a variety of locomotor behaviours and a body mass range spanning three orders of magnitude. We asked how the interaction of body mass and locomotor ecology affects the morphology of the scapula. Univariate traits and the shape of the scapula from the lateral view of 186 species were analysed. Fitting Ornstein–Uhlenbeck models to all univariate traits revealed phylogenetic inertia to be low. Hence, ordinary least squares regressions including an interaction term were used for all traits to test whether the scaling relationships differ in the fossorial and aerial groups when compared with the group characterized by arboreal locomotion, the most probable ancestral sciuromorph condition. We also asked whether the scaling of univariate traits departs from isometry in each of the three locomotor groups. The aerial group was expected to show the highest trait values for a given body mass and the highest slope values, followed by the arboreal and fossorial groups along this sequence. Only a few traits showed a difference in scaling among locomotor groups and/or a distinct allometric pattern. Discrepancies between our expectations and results are discussed in a morphofunctional context.
