The Seliger – Moscow hybrid zone between chromosome races of common shrews – an initial description

Bulatova N.S., Shchipanov N.A., Searle J.B.

P. 111-116

We provide the first description of a hybrid zone between chromosome races of Sorex araneus in Central European Russia. In the area near Lake Seliger (Upper Volga), the locally-distributed Seliger race (diagnostic chromosomes hn, ik, mq, pr, g, o) meets and hybridises with the more widespread Moscow race (gm, hi, kr, no, pq). This hybrid zone appears to be narrow and constrained to the inter-lake isthmus between Lake Seliger and the River Volga system. The hybrid zone may be centred on a minor road. Hybrids occur between the two races but at low frequency. There were three F1 hybrids out of a total of 87 specimens. These were expected to form the maximally long meiotic chain that can be found in the common shrew: a chain-of-eleven (CXI). Such a configuration was observed in meiotic preparations from one adult male F1. Two other complex heterozygote karyotypes were found. The existence of these backcross individuals reflects Robertsonian polymorphism for certain race-specific chromosomes. It is presumed that these various hybrids have reduced fertility, consistent with the narrowness of the hybrid zone and bimodal structure. This is likely to be a “strong” hybrid zone with a greater probability of reduced gene flow and evolution of reproductive isolation than other hybrid zones in the common shrew.DOI: 10.15298/rusjtheriol.6.1.15

• Aniskin V.M. & Lukianova I.V. 1989. [A new chromosome race and the analysis of hybridization zone of two of Sorex araneus (Insectivora, Soricidae) karyoforms] // Doklady Akademii Nauk SSSR. Vol.309. P.1260-1262 [in Russian].
• Bannikova A.A., Bulatova N.S., Krysanov E.Y. & Kramerov D.A. 2003. DNA polymorphism within Sorex araneus and two congeneric species as inferred from inter-SINE-PCR // Mammalia. Vol.67. P.263-274.
• Bannikova A.A., Bulatova N.S. & Kramerov D.A. 2006. Molecular variability in the common shrew Sorex araneus L. from European Russia and Siberia inferred from the length polymorphism of DNA regions flanked by short interspersed elements (Inter-SINE PCR) and the relationships between the Moscow and Seliger chromosome races // Russian Journal of Genetics. Vol.42. P.595-604.
• Barton N.H. & Hewitt G.M. 1985. Analysis of hybrid zones // Annual Reviews of Ecology and Systematics. Vol.16. P.113-148.
• Brünner H., Lugon-Moulin N. & Hausser J. 2002. Alps, genes, and chromosomes: their role in the formation of species in the Sorex araneus group (Mammalia, Insectivora), as inferred from two hybrid zones // Cytogenetic and Genome Research. Vol.96. P.85-96.
• Bulatova N., Searle J.B., Bystrakova N., Nadjafova R., Shchipanov N. & Orlov V. 2000. The diversity of chromosome races in Sorex araneus from European Russia // Acta Theriologica. Vol.45. Suppl.1. P.33-46.
• Harrison R.G. 1993. Hybrids and hybrid zones: historical perspective // Harrison R.G. (ed.). Hybrid Zones and the Evolutionary Process. New York: Oxford University Press. P.3-12.
• Hausser J., Fedyk S., Fredga K., Searle J.B., Volobouev V.T., Wójcik J.M. & Zima J. 1994. Definition and nomenclature of chromosome races of Sorex araneus // Folia Zoologica. Vol.43. Suppl.1. P.1-9.
• Jiggins C.D. & Mallett J. 2000. Bimodal hybrid zones and speciation // Trends in Ecology and Evolution. Vol.15. P.250-255.
• Král B. & Radjabli S.I. 1974. Banding patterns and Robertsonian fusions in the western Siberian population of Sorex araneus (Insectivora, Soricidae) // Folia Zoologica. Vol.23. P.217-227.
• Mercer S.J., Wallace B.M.N. & Searle J.B. 1992. Male common shrews (Sorex araneus) with long meiotic configuration can be fertile: implications for chromosomal models of speciation // Cytogenetics and Cell Genetics. Vol.60. P.68-73.
• Polyakov A.V., Volobouev V.T., Borodin P.M. & Searle J.B. 1996. Karyotypic races of the common shrew (Sorex araneus) with exceptionally large ranges: the Novosibirsk and Tomsk races of Siberia // Hereditas. Vol.125. P.109-115.
• Searle J.B. 1984. Three new karyotypic races of the common shrew Sorex araneus (Mammalia: Insectivora) and a phylogeny // Systematic Zoology. Vol.33. P.184-194.
• Searle J.B., Fedyk S., Fredga K., Hausser J. & Volobouev V.T. 1991. Nomenclature for the chromosomes of the common shrew (Sorex araneus) // Mémoires de la Société Vaudoise des Sciences Naturelles.Vol.19. P.13-22.
• Searle J.B. & Wójcik J.M. 1998. Chromosomal evolution: The case of Sorex araneus // Wójcik J.M. & Wolsan M. (eds.). Evolution of Shrews. Białowieża: Mammal Research Institute, Polish Academy of Sciences. P.219-268.
• Shchipanov N.A. 2007. Understanding the boundaries between chromosome races of common shrews in terms of restricted movement by individual shrews // Russian Journal of Theriology. Vol.6. P.00-00.
• Shchipanov N.A., Kalinin A.A., Oleinichenko V.Yu., Demidova T.B., Goncharova O.B. & Nagornev F.V. 2000. [The technique of studying space usage in Sorex shrews] // Zoologicheskii Zhurnal. Vol.79. P.362-371 [in Russian, with English summary].
• Szałaj K., Fedyk S., Banaszek A., Chętnicki W. & Ratkiewicz M. 1996. A hybrid zone between two chromosome races of the common shrew, Sorex araneus, in eastern Poland: preliminary results // Hereditas. Vol.125. P.169-176.
• Williams D., Hagen A., Runyan J. & Lafferty D. 1971. A method for the differentiation of male meiotic chromosome stages // Journal of Heredity. Vol.62. P.17-22.
• Wójcik J.M., Borodin P.M., Fedyk S., Fredga K., Hausser J., Mishta A., Orlov V.N., Searle J.B., Volobouev V.T. & Zima J. 2003. The list of the chromosome races of the common shrew Sorex araneus (updated 2002) // Mammalia. Vol.67. P.169-178.
• Wójcik J.M., Ratkiewicz M. & Searle J.B. 2002. Evolution of the common shrew Sorex araneus: chromosomal and molecular aspects // Acta Theriologica. Vol.47. Suppl.1. P.139-167.