Divergent mandibular morphology in American mink ( Neogale vison ) fossils suggests novel role in past environments

Abstract The presence and spatial distribution of intraspecific variation impact the evolvability of a species. Understanding this variation may shed light on the natural history and ecological breadth, realized and potential, of specific taxa. Insights from the paleontological record can provide additional information on potential phenotypic variation for species that have adapted to past and present environments. Here, we use the American mink, Neogale vison (Schreber, 1777), as a case study to understand the extent and pattern of mandibular shape variation among extant populations (n = 290) and fossil assemblages (n = 13). We use these data to examine whether the role of N. vison has changed in response to environmental conditions or through time. We found that some fossil N. vison mandibles lie outside the morphospace occupied by extant N. vison and are distinct from modern mink. Fossils from Conard Fissure, Arkansas (n = 8), represent a unique morphotype that likely had higher bite forces than modern N. vison. This morphotype may have allowed N. vison at this site to take advantage of larger or different prey. These results demonstrate both the adaptive potential of N. vison and the fossil record’s ability to reveal unique variation in a lineage.