Supplementary Material for: Karyotype Evolution and Phylogenetic Relationships of Cricetulus sokolovi Orlov et Malygin 1988 (Cricetidae, Rodentia) Inferred from Chromosomal Painting and Molecular Data

Sokolov's dwarf hamster (<i>Cricetulus sokolovi</i>) is the least studied representative of the striped hamsters (<i>Cricetulus barabensis</i> species group), the taxonomy of which remains controversial. The species was described based on chromosome morphology, but neither the details of the karyotype nor the phylogenetic relationships with other <i>Cricetulus</i> are known. In the present study, the karyotype of <i>C. sokolovi</i> was examined using cross-species chromosome painting. Molecular and cytogenetic data were employed to determine the phylogenetic position of Sokolov's hamster and to analyze the potential pathways of chromosome evolution in <i>Cricetulus</i>. Both the chromosome and molecular data support the species status of Sokolov's hamster. Phylogenetic analysis of the <i>CYTB</i> data placed <i>C. sokolovi</i> as sister to all other striped hamsters (sequence divergence of 8.1%). FISH data revealed that the karyotype of <i>C. sokolovi</i> is highly rearranged, with the most parsimonious scenario of its origin implying at least 4 robertsonian events and a centromere shift. Comparative cytogenetic data on Cricetinae suggest that their evolutionary history includes both periods of chromosomal conservatism and episodes of rapid chromosomal change.