Сold Hardiness and Range of the Earthworm <i>Eisenia sibirica</i> (Oligochaeta, Lumbricidae)
A hypothesis of range formation of the earthworm <i>Eisenia sibirica</i> Perel et Graphodatsky, 1984, which is an endemic species of Altai-Sayansk mountain system and is also found on the adjacent plains of Siberia across the valleys of the rivers, was suggested. Limited distribution of the species can be connected with insufficient cold hardiness of the worm stage (-10…-12 <sup>о</sup>С). Plains of Western Siberia lie in the isotherm area of minimum soil temperatures at a depth of 3 cm - -12…-14 <sup>о</sup>С, i. e., on average 2-4 <sup>о</sup>С below tolerable limits for this species. Foothills and mountain soils are warmer, since they obtain much more solid precipitations. Low soil temperatures of the plains apparently “lock up” this species within Altai-Sayansk system. At the same time there is reason to consider the northernmost locations of <i>E. sibirica</i> to be relict.