Meeting Abstract
The evolution of the locomotor apparatus is driven by the phylogenetic heritage of organism, the medium in which it moves and locomotor habits. Mustelids display various locomotor modes ranging from arboreal locomotion to swimming and burrowing. Their evolutionary history shows several returns to an aquatic lifestyle. As semi-aquatic species move both on land and in water, their locomotor apparatus is submitted to the functional constraints of both media. Because the less aquatic forms swim mainly using forelimb paddling we hypothesize functional adaptations of the forelimb, conversely, the more aquatic forms that swim using hind limbs and body undulation should present locomotor adaptations at the level of the hind limbs. We performed 3D scans of the long bones of 87 specimens of 20 mustelid species covering all sub-families. Using traditional landmark-based geometric morphometrics as well as sliding semi-landmarks we quantified the form of both diaphysis and articular surfaces of forelimb long bones. Using this morphometric dataset, we investigate the influence of locomotor behavior while taking phylogeny and body size into account. Preliminary results suggest that aquatic species show morphological differences in forelimb long bone shape compared to other species. Moreover, the most aquatic species appear highly specialized and show morphological differences in both limb pairs. Although these results suggest adaptive differences in the limbs of semi-aquatic mustelids further studies investigating forelimb-hindlimb shape covariation, the musculature and kinematics of locomotion are needed.
