Additional files [RJEE Vol. 7 (1). 2022 – 1]

• Fig. 1. Map of changes in the borders of the Samara Region in the XIX and XX centuries [1]
• Fig. 2. The current distribution of russet (1), little (2) and speckled (3) ground squirrels in the Samara region (according to the data of the colonies of 2011–2021)
• Fig. 3. Results of DNA analysis of individuals of russet (m) and little (p) ground squirrels and their hybrid (p/m) by gene p53. M – mass marker (pBR322/HpaIII)
• Fig. 4. Sonograms of sound signals of russet and little ground squirrels and their hybrid: A – S. major; B – S. major×S. pygmaeus; C – S. pygmaeus
• Fig. 5. Dendrogram of phylogenetic relationships of haplotypes of speckled ground squirrels (Spermophilus suslicus) from the Ulyanovsk and Samara (Syzran) regions based on the analysis of sequences of the control region (1018 bp, model HKY+G, BIC = 3974.4, InL = – 1896.1)  and the Cyt b gene (1119 bp, HKY model, BIC = 4254.8, InL = – 2029.5) mtDNA by the maximum likelihood (ML) method. The outer group is a russet ground squirrel (S. major). The numbers in the nodes indicate the level of bootstrap support. Photo of a speckled ground squirrel – © Sergey Titov
• Audio file of calls of parent species (Spermophilus major; S. pygmalus) and hybrids (S. major x S. pygmalus)