Evolutionary patterns of Marmota: 2D and 3D geometric morphometrics of the mandible and cranium. Evoliutsionnï’e tcherti Marmota: 2-kh I 3-kh mernye geometritcheskie I morfometritcheskie priznaki nijneï tcheliusti I tcherepa. [Canevas évolutifs de Marmota : morphométrie géométrique 2D et 3D de la mandibule et du crâne].

Résumé

Mandibles and crania of all living marmot species are analyzed using 2D and 3D geometric morphometric techniques. Ontogenetic trajectories are compared in a subset of species. Allometry accounts for an important proporion, altough not for the majority, of shape variation during pos-natal ontogeny of the cranium and mandible. Interspecific divergence of allometries is significant but small, and most differences in relation to phylogeny appear early in the ontogeny. A very different role of allometry as a source of morphological novelties can be speculated on in earlier stages of marmot evolutionary history, when a highly distinctive cranial shape evolved in concomitance with two-fold increase in size. Also, adults of all marmot species are compared. Different datasets suggest slightly different phenetic relationships, but a general pattern in the morphological evolution of marmots can be inferred. Support is found for marmot subgenera, altough highly divergent morphologies evolved in some species either because of a long evolutionary history and distinctive ecology (M. monax cranium) or because of geographic isolation in small populations (M. vancouverensis mandible and cranium). These findings indicate the usefulness of complementing molecular phylogenetic analyses with morphological studies to understand the evolutionary history of a clade, and for a thorough characterization of population divergence.