Comparative studies among seven populations of 2n = 60 S. leucodon employing classic cytogenetics (G- bands, C-bands, AgNOR-staining), fluorochrome staining, and fluorescence in situ hybridization of telomeric and rDNA probes are reported here for the first time. The studied specimens were assigned to two cytotypes: 2n = 60W and 2n = 60R. The basic karyotype of both cytotypes consisted of eight pairs of subtelocentric and 21 pairs of acrocentric autosomes, subtelocentric X and acrocentric Y chromosomes. Both cytotypes had variable numbers of B-chromosomes (1–3) and variable numbers of autosomal arms (NFa = 74–76) caused by amplification (deletion) of heterochromatin short arms in the second pair. The short arms of subtelocentric chromosomes were comprised of heterochromatin in both cytotypes. Nucleolar organizer regions (NORs) and rDNA clusters were detected at telomeric sites of the short arms in pairs Nos. 3, 5, 6, 9, and 13 in cytotype W, and in the short arms of pair No. 6, 8, 12, 13, and 16 in cytotype R. Different locations of rDNA clusters allowed unambiguous discrimination between two S. leucodon cytotypes possessing the same 2n = 60 and similar NFa (74–76) variability. Our findings suggest a high level of chromosomal divergence, which means that it is possible to consider these cytotypes as a well-differentiated, chromosomal lineage within the leucodon group.
Using both nuclear and mitochondrial sequences, we demonstrate high genetic differentiation in the genus Talpa and confirm the existence of cryptic species in the Caucasus and Anatolia, namely, T. talyschensis Vereschagin, 1945, T. ognevi Stroganov, 1948, and Talpa ex gr. levantis. Our data support four clades in the genus Talpa that showed strong geographical associations. The 'europaea' group includes six species from the western portion of the genus' range (T. europaea, T. occidentalis, T. romana, T. caeca, T. stankovici, and T. levantis s.l.); another three groups are distributed further east: the 'caucasica' group (Caucasus), the 'davidiana' group (eastern Anatolia and Elburz) and T. altaica (Siberia). The phylogenetic position of T. davidiana was highlighted for the first time. The order of basal branching remains controversial, which can be attributed to rapid diversification events. The molecular time estimates based on nuclear concatenation estimated the basal divergence of the crown Talpa during the latest Miocene. A putative scenario of Talpa radiation and issues of species delimitation are discussed.
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