The theriofaunistic zoning of northern Eurasia

For the purpose of zoning on the basis of theriofauna, Northern Eurasia was considered within the boundaries of the Soviet Union in 1991 and was divided into 245 mapping units. Mapping units were marked on the World Vegetation Map at a scale of 1: 2000000. Each mapping unit occupied a territory within the limits of a natural subzone with a latitudinal distance of 10°. A list of mammal species was generated for each unit. Jaccard similarity coefficients were calculated for these lists; the coefficients were used as the basis for performing cluster analysis of theriofauna of the mapping units. The results of calculations were used to create a hierarchical classification, which includes three theriofauna regions divided into seven subregions. They were classified as island or mainland. All the subregions (except one) were delimited into 18 provinces and 17 districts; one of the districts was delimited into four subdistricts. Environmental factors that correlate with heterogeneity of theriofauna within the studied territory were described. The proposed zoning is 1.9–3 times more informative than previously developed schemes and takes into account 69% of the variance of the similarity coefficients of the faunas of specific regions (coefficient of multiple correlation is 0.83). The association with environmental factors and natural conditions may explain 83% of the heterogeneity of the theriofauna (correlation coefficient is 0.91). Comparing the results of zoning that were carried out for different classes of terrestrial vertebrates, we found significant similarity between causes of fauna heterogeneity (zonal features, remoteness, sun exposure, and their combined effect). In addition, the differences in tolerance to the environment among the studied animal classes resulted in substantial discordance of the boundaries of the described taxa and their hierarchy. This discordance was found during zoning. Because of this, general conclusions concerning the heterogeneity of the fauna of terrestrial vertebrates can be made only after the total analysis of their fauna is completed.