Abstract
The common shrews, Sorex araneus Linnaeus, 1758, inhabiting the territory of Belarus, are characterized by a significant variation in the frequency of Robertsonian (Rb) translocations. The frequency clines for translocations specific of three chromosome races: the West Dvina (gm, hk, ip, no, qr), Kiev (g/m, hi, k/o, n, p, q, r), and Białowieża (g/r, hn, ik, m/p, o, q) have already been studied in this territory. In this communication we report new data on polymorphic populations with Rb metacentrics specific of the Neroosa race (go, hi, kr, mn, p/q) in south-eastern Belarus, analyse the distribution of karyotypes in southern and central Belarus and draw particular attention to the fixation of the acrocentric variants of chromosomes in this area. The results show that certain Rb metacentrics specific of the Neroosa, West Dvina, Kiev, and Białowieża races (namely, go and pq; ip; ko; hn and ik, respectively) are absent in many polymorphic populations. Thus, the karyotypic differentiation of S. araneus in the studied area is determined by unequal spread of different Rb translocations and by fixation of acrocentric variants of specific chromosomes.
Highlights
The common shrew, Sorex araneus Linnaeus, 1758, a species inhabiting Eurasia, is a model object for population genetic studies due to its exclusive chromosomal polymorphism
“A chromosome race of Sorex araneus is defined as a group of geographically contiguous or recently separated populations which share the same set of metacentrics and acrocentrics by descent” (Hausser et al 1994)
Chromosome races of S. araneus differ in the composition and numbers of metacentrics, which were formed by Robertsonian (Rb) translocations involving 10 pairs of acrocentric chromosomes, g, h, i, k, m, n, o, p, q, and r (Searle et al 1991, Hausser et al 1994)
Summary
The common shrew, Sorex araneus Linnaeus, 1758, a species inhabiting Eurasia, is a model object for population genetic studies due to its exclusive chromosomal polymorphism (for review, see: Wójcik et al 2002, Shchipanov and Pavlova 2016). Four metacentric autosomes (af, bc, jl, and tu) and sex chromosomes (XX in females and XY1Y2 in males) are characteristic of species S. araneus (acrocentric morphs of chromosome arms j and l sporadically occur in populations through the species area), while ten autosomal arms (g, h, i, k, m, n, o, p, q, and r) can be presented as acrocentrics or be fused as metacenetrics (Searle et al 1991). “A chromosome race of Sorex araneus is defined as a group of geographically contiguous or recently separated populations which share the same set of metacentrics and acrocentrics by descent” (Hausser et al 1994). Chromosome races of S. araneus differ in the composition and numbers (one–five pairs) of metacentrics, which were formed by Robertsonian (Rb) translocations involving 10 pairs of acrocentric chromosomes, g, h, i, k, m, n, o, p, q, and r (Searle et al 1991, Hausser et al 1994). Monomorphic karyotypes are characteristic of some races (all race-specific Rb translocations are fixed), while polymorphism for 2–5 translocations was revealed in majority of chromosome races (see list of Shchipanov and Pavlova 2016)
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