Hares from the Late Pleistocene of Ukraine: a phylogenetic analysis and the status of Lepus tanaiticus (Mammalia, Lagomorpha)

Hares (genus Lepus) are widely distributed in Europe, and they are adapted to various types of habitats. Many species are known to hybridise, and previous molecular genetic studies have revealed recurrent introgressions between species at all stages of the genus's radiation. The Don hare (Lepus tanaiticus) was described from the Late Pleistocene of the Southern Urals and subsequently reported from coeval deposits of various regions of northern Eurasia. It is morphologically close to the mountain hare (Lepus timidus) and recent studies of mitochondrial DNA questioned its status as an independent species. Here we compare cytochrome b and control-region sequences of mtDNA of arctic Lepus, including, for the first time, eight specimens from Late Pleistocene localities of Ukraine, in order to analyse the phylogenetic relationships between representatives of different taxa. The phylogenetic tree and haplotype network analyses do not support the taxonomic distinctness of the Don hare, and only specimens of Lepus arcticus and Lepus othus form monophyletic groups based on the control-region sequences. Instead, L. tanaiticus are scattered among specimens of L. timidus. The obtained results support the hypothesis that the Don hare is an ancient morphotype of L. timidus, and its distinctive morphological traits are the result of increased geographical variation of the latter due to range expansion and adaptation to the specific conditions of the periglacial biome, similarly to other Late Pleistocene small-mammal species.