Biotopic distribution of three sympatric species of lizards (Lacertilia) in the Terek sands

The background species of the saurofauna of the southeastern periphery of the Tersk Sands in the early 1980s were Phrynocephalus guttatus (Gmelin, 1789), Eremias velox (Pallas, 1771) and Eremias arguta (Pallas, 1773). Research conducted in 1983-1984 showed that each of them had different preferred biotopes: Phr. guttatus - blown sands, E. arguta - fixed sands, E. velox - scattered shrubbery. At the turn of the 20th and 21st centuries, Phr. guttatus completely disappeared in the study area on the southeastern periphery of the Tersk Sands, and after 2008 - E. velox. Currently, the territory is inhabited by E. arguta and the widespread Lacerta strigata Eichwald, 1831. The rapid changes in the composition of the saurofauna can be explained primarily by the strict biotopic confinement of lizards in conditions of total steppification of the Terek sands. The transformation of landscapes brought stenobiont species, in the conditions of the Eastern Pre-Caucasus psammophile species of Turanian genesis, to the brink of extinction and created favorable conditions for eurybiont and/or steppe forms. If existing trends continue, we can expect the complete disappearance of such obligate psammophiles as Phr. mystaceus (Pallas, 1776) and Phr. guttatus in the Terek Sands. They may be followed by Trapelus sanguinolentus (Pallas, 1814) and E. velox. In this case, biotopic preferences of a species determine their current and prospective sociological status.