Aftereffects of muskrat introduction in Western Siberia: Morphological and functional aspects

Abstract

The muskrat (Ondatra zibethicus L.) allochronic samples at different stages of its introduction in Western Siberia are compared by geometric morphometrics; the comparison demonstrates directed changes in the size and shape of mandible as well as the changes in its morphological and functional characteristics as a feeding organ. As is shown, a rapid initial divergence of the northern (Yamal Peninsula) and southern (Kurgan oblast) muskrat populations, accompanied by emergence of morphological differences between them, is followed by biocenotic adaptation with gradual (over half a century) directed parallel changes in the mandible shape associated with its functional properties in the south and north of the region. The range of morphogenetic transformations of the allochronic samples of the northern group is larger as compared with the southern group, which is explainable by the more severe environmental conditions in the Yamal forest-tundra. Both populations display a statistically significant decrease in the morphological disparity of the mandible shape from the mid-20th century to its end. Leveling of the muskrat mandible size between the northern and southern populations by the end of the last century excludes any allometric effects in the observed geographic and chronographic differences in the mandible shape. Therefore, microevolutionary transformations of the morphogenesis of other invasive species can be implemented on a historical time scale, that is, relatively rapidly. This should be taken into account when forecasting potential local biocenotic crises. The model of the long-term morphogenetic aftereffects of the muskrat introduction in Western Siberia confirms the possibility of rapid adaptive morphogenetic, morphological, and functional changes in invasive mammalian species introduced into new communities.