Variability of alarm call in ground squirrels of major group (Rodentia, Sciuridae, Spermophilus) as a model of geographic species formation

The variability of alarm calls in ground squirrels of the major group was analyzed. Parameters of polynomial equations were used as variables for characterizing the frequency modulation of signals. The range of the populations discussed is from the Volga River to the Gobi Altai. Four main clusters of the populations were distinguished based on the results of multivariate analysis. They correspond with four species of ground squirrels: (1) Spermophilus carruthersi (Thomas 1912); (2) S. brevicauda (Brandt 1843); (3) S. erythrogenis (Brandt 1841); and (4) S. major (Pallas 1778). Brakes in the variability between the population groups (main clusters) are clearly marked by four geographical barriers: (1) Turgai; (2) Balkhash-Alakol; (3) Irtysh-Zaisan; and (4) Tarbagatai. Three of these barriers separating populations of the major group are in southeastern Kazakhstan. The results obtained correspond to the concept of geographical species formation (Meyr 1944).