Geographical variability of the little ground squirrel (Spermophilus Pygmaeus): A bioacoustic analysis

The geographical variability of alarm call in Spermophilus pygmaeus and the difference between this species and S. musicus were investigated. Alarm calls of 96 individuals from 13 localities (from the Sea of Azov to Karakum adjacent to the Aral Sea) were analyzed. Parameters of polynomial equations were used as variables for the characterization of frequency modulations of the signal. The cluster and principal component analyses have revealed a significant level of distinctions between S. pygmaeus dwelling in the territories to the east and west from the Volga River. The possibility of contacts between populations inhabiting the both river banks was shown. The presence of breaks in the signal variability between the populations appears to be a consequence of isolation in refuges during the Quaternary period. The close similarity of the sound signal in S. musicus and S. pygmaeus (inhabiting to the west from the Volga) allows us to consider S. musicus as a subspecies oí Spermophilus pygmaeus musicus.