Stoat - Evolution

Evolution

The stoat's direct ancestor was Mustela palerminea, a common carnivore in central and eastern Europe during the Middle Pleistocene, and probably reached North America in its current form during the late Blancan or early Irvingtonian. The stoat is the product of a process begun 5–7 million years ago, when northern forests were replaced by open grassland, thus prompting an explosive evolution of small, burrowing rodents. The stoat's ancestors were larger than the current form, and underwent a reduction in size to exploit the new food source. The stoat first arose in Eurasia, shortly after the long-tailed weasel arose as its mirror image in North America 2 million years ago. The stoat thrived during the Ice Age, as its small size and long body allowed it to easily operate beneath snow, as well as hunt in burrows. The stoat and the long-tailed weasel remained separated until half a million years ago, when falling sea levels exposed the Bering land bridge.

Combined phylogenetic analyses indicate the stoat's closest living relative is the mountain weasel (Mustela altaica), though it is also closely related to the least weasel (Mustela nivalis) and long-tailed weasel (Mustela frenata). Its next closest relatives are the New World Colombian weasel (Mustela felipei) and the Amazon weasel (Mustela africana).