Taxonomic Interpretation of Allopatric Mammalian Forms on the Example of Two Karyoforms of Microtus (Terricola) subterraneus (Rodentia, Arvicolinae) from Eastern Europe

Abstract

New European pine vole records from the Novgorod, Kaluga, Voronezh, and Belgorod oblasts were studied by sequencing of the mtDNA cytb gene (1143 bp) and by karyotyping (routine staining and G-banding techniques). The results enabled us to summarize chromosome variability of this species throughout Eastern Europe. In the sample studied, two geographically replacing chromosomal forms have been identified: northern, 2n = 54 (Novgorod and Kaluga oblasts), and southern, 2n = 52 (Voronezh and, presumably, Belgorod oblasts). Our data make the boundaries of these two karyoforms in Eastern Europe more precise and testify to intraspecific level of their taxonomic differentiation.

High molecular variability in three pine vole species of the subgenus Terricola ( Microtus , Arvicolinae) and plausible source of polymorphism

“…subterraneus , and M . majori as well the isolated position of the latter species from the other two, as was revealed in the majority of previous publications (Baskevich, 1997; Baskevich et al, 2018; Baskevich, Potapov, Khlyap, et al, 2016; Jaarola et al, 2004; Martínková & Moravec, 2012; Mezhzherin et al, 1995; Tougard, 2017). The result is in accordance with paleontological data and the ecological preferences of extant species of the subgenus Terricola and their ancestral fossil forms.…”

“…Despite differences between the subgenus structure schemes suggested in these three studies (Jaarola et al, 2004;Martínková & Moravec, 2012;Zagorodnyuk, 1988), they unanimously noted the separation of M. majori from M. daghestanicus and M. subterraneus that was confirmed by molecular (Baskevich et al, 2018;Baskevich, Potapov, Khlyap, et al, 2016;Bogdanov, Khlyap, et al, 2020;Tougard, 2017), karyotypic (Baskevich, 1997) and allozyme studies (Mezhzherin et al, 1995). Nevertheless, it should be stressed that the majority of these studies of molecular genetic variability within subgenus Terricola considered only one mitochondrial gene (cytb), and the analyses were conducted on only a few specimens of each species.…”

“…Other scientists (Corbet, 1978; Gromov & Polyakov, 1977; Ognev, 1950) recognized subterraneus and majori forms as distinct species, and daghestanicus form as a subspecies of majori. Later, different karyotypes were described in all of these forms: 2n = 54, NF = 60 in majori; 2n = 38–54, NF = 58 in daghestanicus (Akhverdyan et al, 1992; Baskevich et al, 1984; Baskevich, Potapov, Khlyap, et al, 2016; Ivanov & Tembotov, 1972; Khatoukhov et al, 1978; Lyapunova et al, 1988); 2n = 52–54, NF = 60 in subterraneus (Baskevich et al, 2007, 2018; Bulatova et al, 2007; Macholán et al, 2001; Meylan, 1972; Mitsainas et al, 2010; Sablina et al, 1989; Zagorodnyuk, 1988; Zima & Kral, 1984). These karyotypic peculiarities served as the basis for recognition of all of the forms as distinct species: Microtus majori Thomas, 1906 (Major's pine vole), Microtus daghestanicus Shidlovsky, 1919 (the Caucasus or Daghestan pine vole), and Microtus subterraneus de Selys‐Longchamps, 1836 (the common or European pine vole) (Ivanov & Tembotov, 1972; Khatoukhov et al, 1978; Niethammer & Krapp, 1982; Baskevich et al, 1984).…”

“…daghestanicus , and M . subterraneus differ from each other in their molecular genetic characteristics (Baskevich et al, 2018; Baskevich, Potapov, Khlyap, et al, 2016; Baskevich, Potapov, & Mironova, 2016; Bogdanov, Khlyap, et al, 2020; Jaarola et al, 2004; Macholán et al, 2001; Martínková & Moravec, 2012; Mezhzherin et al, 1995; Tougard, 2017) as well as in their ecological preferences (Baskevich, 1997; Shvarts, 1985; Tembotov & Khatoukhov, 1979; Zagorodnyuk, 1992). Recent taxonomic checklists (Musser & Carleton, 2005; Pavlinov & Lissovsky, 2012) supported the specific status of M .…”

“…Three chromosome forms are revealed in M . subterraneus : two with 2n = 54, differing in the heterochromatin band size of the X chromosome and its morphology, and one with 2n = 52, which supposedly emerged due to a Robertsonian fusion (Baskevich et al, 2007, 2018; Bulatova et al, 2007; Macholán et al, 2001; Meylan, 1972; Mitsainas et al, 2010; Sablina et al, 1989). According to Zagorodnyuk (1991), the 52 chromosome form inhabiting southern Europe may be assigned to a separate species, Microtus dacius Miller, 1911, while the former name, M .…”