Genetic Variability of the Laxmann’s Shrew (Sorex caecutiens Laxmann, 1788) of the Kolyma River Basin and Chukotka

Nucleotide sequence polymorphism and haplotypic diversity of the cytochrome b gene were studied in samples of the Laxmann’s Shrew subspecies- Sorex caecutiens koreni from the populations of the Kolyma River basin and Chukotka Peninsula. Fifty-six cytb haplotypes differing among themselves by 87 mutations in 84 sites were found. The cytb haplotypes of individuals of the subspecies S. c. koreni and S. c. macropygmaeus were shown to belong to the same maternal mtDNA lineage; their monophyletic origin from the same ancestral haplotype Scb1 and the presence of identical cytb haplotypes in both subspecies were revealed. The mutual isolation of the shrew populations in the upper basin of the Kolyma River and Chukotka is shown. The proportion of intrapopulation genetic variability is 95.74%, intergroup variability is 5.74%, and intragroup variability is 1.48%, which reflects a very high level of intrapopulation variability of cytb haplotypes in the studied groups of S. c. koreni , their monophyletic origin, and the genetic unity of the Chukchi samples. The values of molecular diversity indices testify to the stability of populations that have had a high value of effective abundance for a long time.