Chromosome polymorphism in a population of Sorex araneus L. at Białowieza
Fedyk, S.
Folia Biologica 28(2): 83-120
1980
ISSN/ISBN: 0015-5497 PMID: 7428984 Document Number: 155737
Chromosome studies of 230 common shrews (S. araneus L.) caught in 3 different ecosystems of the Bialowieza Primeval Forest were performed. The karyomorphs of these shrews were determined; individual chromosome identification was aided by G-banding technique, analysis of male meiotic preparations, and data from individuals bred in captivity and embryos. In the Bialowieza population the 8th pair of autosomes is homozygotic (type A homozygotes), pairs 4, 5 and 7 are polymorphic and the remaining pairs of autosomes are homozygotic (type M homozygotes). Because the frequencies of single-armed chromosomes were very low in all the polymorphic pairs, only 5 out of the theoretically possible 27 karyomorphs were identified in the sample. Variations were found in the frequencies of single-arm chromosomes in all polymorphic pairs in consecutive years, while the heterozygosity of the population decreased regularly during the study period. The studied population shows a transient polymorphism for chromosome pairs 4, 5 and 7, the single-armed chromosomes being in the process of elimination. A relation between the ecosystem and the chromosome formula in relation to the heterozygotes of pair 5 was found.