PATTERNS OF GEOGRAPHIC-VARIATION IN THE SKULL OF NEARCTIC ERMINE (MUSTELA-ERMINEA)

There is significant geographic variation among samples of 13 craniometric characters of North American ermine. Most of the skull character variance reflects differences in size and is clinal. Variation in skull size is better explained by temperature and precipitation variables than by geographic distance, suggesting that environmentally ordered selection for size has been superimposed on any size differentiation that occurred during isolation in refugia. Distinctive groups of samples reflect possible refugial populations in Eastern Beringia, in periglacial refugia south of the Wisconsin ice in eastern North America, and in one or more western North American refugia. -from Author