The humerus of South American caviomorph rodents: shape, function and size in a phylogenetic context

MORGAN, CECILIA C.; ALVAREZ, ALICIA

JOURNAL OF ZOOLOGY (1987)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2013 vol. 290 p. 107 - 116

0952-8369

South American caviomorph rodents comprise four major lineages encompassingwide taxonomic and ecological diversity, but the morphological diversity of theirpostcranial skeleton has not been thoroughly explored using phylogenetic comparativemethods. The main goal of this work is to analyze their humerus usinggeometric morphometrics in a phylogenetic context and attempt to tease apart theinfluence of locomotory preferences and shared evolutionary history on morphologicalvariation. We examined 28 genera in 9 families representing all majorclades. Humeral shape was captured by 13 landmarks and four semilandmarks in2D. In the morphospace of the first two principal components, most taxa werelocated near the origin along both axes. Fossorial octodontoids were apart fromthis central group. Most caviids were separated in one extreme of the morphospace;the specialized digging ctenomyid Ctenomys, the fossorial chinchillid Lagostomusand the generalized cavioid Cuniculus were located at the opposite end.Phylogenetic signal was significant. Regressions of shape on size were not significant;regression of shape on habit was significant for raw data and not significantafter phylogenetic control. Humeral shape variation was primarily associated withthe phylogenetic structure of the group; additionally, some morphological traitswere associated with particular habits and interpreted as functional specializations.This association between humeral shape and both phylogeny and habit atdifferent hierarchical levels suggests early ecomorphological diversification ofcaviomorphs