The karyotype of Sorex arcticus maritimensis (Insectivora, Soricidae) and its systematic implications

Abstract

The chromosomes of Sorex arcticus maritimensis are described for the first time and their banding pattern (R- and C-bands) compared with those of Sorex araneus. The results provide further evidence for the monophyletic origin of the araneus–arcticus group and clearly indicate that the primary mechanisms of chromosomal reorganization in this group have been Robertsonian and tandem translocations. The basic karyotype of S. a. maritimensis was found to differ from that of S. a. arcticus in having a different fundamental number (34 vs. 38) but the same diploid number. A full understanding of the karyotypic differences between these taxa requires further work. Whatever the exact nature of the differences, they increase the likelihood of an independent specific status for S. a. maritimensis as suggested by the results of an earlier morphometric analysis.

Karyotype Evolution of Eulipotyphla (Insectivora): The Genome Homology of Seven Sorex Species Revealed by Comparative Chromosome Painting and Banding Data

“…arcticus, S. antinorii, S. asper, S. coronatus, S. daphaenodon, S. granarius, S. maritimensis, S. satunini and S. tundrensis [Volobuev and van Zyll de Jong, 1988;Zima et al, 1998;Brunner et al, 2002]. The group is well-studied due to the unusual sex trivalent XY1Y2 in males, with a compound X chromosome resulting from centric fusion of an autosome and an X [Sharman, 1956].…”

Chromosome banding analysis of two shrews of the cinereus group: Sorex haydeni and Sorex cinereus (Insectivora, Soricidae)

“…The tendency of karyotypic evolution in the araneus group to progress from high to low chromosome numbers by means of Robertsonian and tandem translocations (Volobouev and van Zyll de Jong 1988;Volobouev 1989) suggests that similar processes may have been involved in the cinereus group. If this were so, we could interpret the karyotype of S. haydeni as apomorphic relative to that of S. cinereus.…”

“…Chromosome banding techniques have been particularly helpful in analysing the phylogenetic relationships in the araneus group (Volobouev and van Zyll de Jong 1988;Volobouev and Catzeflis 1989;Volobouev 1989) and have provided, hitherto, the only certain means for discriminating some of its species (Hausser et Neet and Hausser 1991). None of the other abovementioned species-groups in Sorex have, to date, been studied by the use of chromosome banding.…”

Biogeographic and Conservation Significance of the Occurrence of the Canadian EndemicSorex maritimensis(Maritime Shrew) in Northern New Brunswick

“…Smith (1939) was the rst to recognize the unique nature of maritime populations of the shrew then known as Sorex arcticus Kerr (Arctic Shrew), ascribing the subspeci c epithet maritimensis to populations from mainland Nova Scotia. On the basis of morphological and karyological evidence, van Zyll de Jong (1983) and Volobouev and van Zyll de Jong (1988) suggested maritimensis as an entity likely speci c from S. arcticus. Stewart et al (2002) used cytochrome-b genetic sequence data to demonstrate the speci c status of S. maritimensis Smith (Maritime Shrew) and formally proposed that the species be recognized as distinct.…”