Chromosome Study of the Common Mole Rat (Tachyoryctes splendens) from Different Localities in Ethiopia
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Date
2005-06
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Addis Ababa University
Abstract
The common mole rat, Tachyoryctes splendens, belongs to family Rhizomyidae or Muridae
(Mammalia; Rodentia). Somatic chromosomes of the species were studied from 9 localities in
Ethiopia (Mugo, Masha, Bure, Ziway, Asebe Teferi, Alemaya, Entoto, Sebeta and Debre Sina)
using the standard Giemsa staining and C-banding techniques. Six different karyotypic forms
were found. These variations were revealed as differences in chromosome morphology,
autosomal fundamental number, amount and distribution of heterochromatin. However, there was
no variation in diploid chromosome number and specimens from all the localities had 2n=48. The
six karyotypic forms had the following karyotypic formulae: Mugo, Masha and Bure (12m + 10st
+ 26a), Debre Sina (10m + 8st + 30a), Ziway (8m + 12st + 28a), Asebe Teferi (8m + 4st + 36a),
Alemaya (8m + 6st + 34a), and Entoto and Sebeta (7m + 1 sm + 2st + 38a). C-banding revealed
that, in addition to the Y-chromosome (except in Entoto), 12, 12, 36, 4, 6, 4, 4 autosomes in
Mugo, Masha, Ziway, Asebe Teferi, Alemaya, Entoto and Sebeta were C-positives, respectively.
The telomeric region of the long arm of the X-chromosome was also C-positive in animals from
Entoto and Sebeta. The present study did not confirm the earlier suggestions that the number of
biarmed chromosomes of T. splendens decreases with the increase in aridity and the number of
heterochromatic arms may exhibit an altitude gradient. We recommend further studies like Gbanding,
zoogeographical, physiological and hybridization studies on T. splendens from different
parts of the distribution range of the species so that the results could supply information to reveal
factors associated with the existing variations, and to draw a valid conclusion that could be used
in clearing the taxonomic uncertainties in this animal.
Key words/ Phrases: Tachyoryctes splendens, chromosome, karyotype, C-banding, Ethiopia
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Keywords
Tachyoryctes splendens, chromosome, karyotype, C-banding, Ethiopia