Functional and Phylogenetic Aspect in Modularity of Palearctic Mustelids (Carnivora, Mustelidae) Mandible

Abstract

Abstract Geometric morphometrics was used to investigate morphological integration and modularity in mustelid mandible. A set of 16 two-dimensional landmarks was digitized on the mandibles of 14 extant species of Palearctic Mustelidae (genera Enhydra, Gulo, Meles, Lutra, Martes, Mustela). The original data size-corrected data and phylogenetically independent contrasts (PICs) were analyzed. Several hypotheses were tested: two and three-modules with the masseteric fossa included in corpus or ramus of the mandible. As a result, the two-module hypothesis (subdivision into the alveolar region and the ascending ramus) with masseteric fossa included in corpus for all sets of data was supported. A clear modularity in mustelid mandible is seen at interspecific level, whereas there was large within species covariation between mandibular corpus and ramus. The allometry correction reduces estimates of covariation for the mustelid mandibles. Due to the analysis of PICs the shape changes with maximum evolutionary covariation were found: elongated, sloped backward ramus and thick corpus.