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steppe polecat
The steppe polecat (''Mustela eversmanii''), also known as the white or masked polecat, is a species of mustelid native to Central and Eastern Europe and Central Asia. It is listed as Least Concern by the IUCN because of its wide distribution, occurrence in a number of protected areas, and tolerance to some degree of habitat modification.〔
It is generally of a very light yellowish colour, with dark limbs and a dark mask across the face.〔 Compared to its relative, the European polecat, the steppe polecat is larger in size and has a more powerfully built skull.〔
The steppe polecat is a nomadic animal which typically only settles in one area until its prey, mainly ground squirrels, are extirpated.〔 It mates from March to May, and generally gives birth to litters of three to six kits, which attain their full growth at the age of two years.〔 It hunts for larger prey than the European polecat, including pikas and marmots.〔
==Evolution==
The earliest true polecat was ''Mustela stromeri'', which appeared during the late Villafranchian period. It was considerably smaller than the present form, thus indicating polecats evolved at a relatively late period. The steppe polecat's closest relatives are the European polecat and black-footed ferret, with which it is thought to have shared ''Mustela stromeri'' as a common ancestor. The steppe polecat likely diverged from the European polecat 1.5 million years ago based on IRBP, though cytochrome b transversions indicate a younger date of 430,000 years.〔Sato, J., T. Hosada, W. Mieczyslaw, K. Tsuchiya, Y. Yamamoto, H. Suzuki. 2003. ''(Phylogenetic relationships and divergence times among mustelids (Mammalia: Carnivora) based on nucleotide sequences of the nuclear interphotoreceptor retinoid binding protein and mitochondrial cytochrome b genes )''. Zoologial Science, 20: 243-264.〕 As a species, the steppe polecat represents a more specialised form than the European polecat in the direction of carnivory, being more adapted to preying on larger rodent species; its skull has a stronger dentition, its projections are more strongly developed and its muscles of mastication are more powerful. The steppe polecat's growth rate is also much slower than the European polecat's, as its skull undergoes further development at an age when the European polecat attains full growth. The species may have once been present in Pleistocene central Alaska.〔ANDERSON, E. 1973. Ferrets from the pleistocene of central Alaska. J. Mammal. 54: 778-779〕
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