GEOGRAPHIC VARIATIONS IN THE SHAPE OF THE UPPER TOOTHROW OF THE ARTCIC FOX (VULPES LAGOPUS L. 1758): EFFECTS OF ASYMMETRY AND ALLOMETRY

Geographic variations in the shape of the upper cheek toothrow were studied using geometric morphometrics. For this, 288 specimens from 19 localities (North America, Eurasia, and Pacific and Arctic islands) were employed. Monomorphism of the toothrow for mainland foxes, both from North America and Eurasia, as well as the foxes from Greenland and St. Lawrence Island was found. The Arctic foxes of four Pacific island populations, i.e. two from the Commander Islands and two from the Pribilof Islands, differ significantly from the mainland counterparts in toothrow shape. The Arctic foxes from the Mednyi Island, the Bering Island and the Pribilof Islands differ from each other by toothrow shape as well. The Mednyi Island Arctic foxes show the shortest toothrow, a wide hard palate, and the most massive teeth. On the contrary, the Pribilof Islands Arctic foxes are the most small-toothed. Allometry does not affect geographic variations in the shape of the Arctic fox toothrow. High-level fluctuating asymmetry is found in the Mednyi Island and St. George Island Arctic foxes. Most probably the high level of fluctuating asymmetry is conditioned by both the extremely low genetic diversity as the result of a dramatic numbers decline in the recent past and the strong impact of heavy metals as the result of a coastal diet. We suppose that the same reasons. i.e. low genetic diversity and coastal diet, could have determined the high level of fluctuating asymmetry of the Arctic fox toothrow on the St. George Island.