title: Genetic variation in the African rodent subfamily Otomyinae (Muridae). II. Chromosomal changes in some populations of Otomys irroratus.
abstract: Chromosome-banding studies have been carried out on 31 specimens of Otomys irroratus from six localities. Light-microscope preparations of chromosomes were obtained from cultures of fibroblasts, spleen lymphocytes, peripheral blood lymphocytes, and directly from bone marrow. Karyotypic variability, both numerical and morphological, was detected in three populations. Diploid numbers ranged from 2n = 23 to 2n = 32. Intrapopulation differences were chiefly caused by variation in the number of copies in two pairs of small, biarmed, partly heterochromatic autosomes suggestive of B chromosomes. A major morphological variation in the karyotypes involved the presence of seven pairs of biarmed autosomes with totally heterochromatic short arms in the populations distributed to the west of 26 degrees 57' E. To the east of this longitude, populations of this species exhibited mostly acrocentric autosomes. G-banding patterns of these karyotypes and those of a karyotype from a previous study (Robinson and Elder, 1987) were compared. A chromosome originating from a tandem fusion, possibly leading to partial reproductive isolation, was found in one population. Possible implications of these results for mechanisms of speciation are discussed.
authors.affiliation: Biology Department, University of Natal, Durban, South Africa.
authors.forename: G
authors.initials: G
authors.lastname: Contrafatto
authors.forename: J A
authors.initials: JA
authors.lastname: Meester
authors.forename: K
authors.initials: K
authors.lastname: Willan
authors.forename: P J
authors.initials: PJ
authors.lastname: Taylor
authors.forename: M A
authors.initials: MA
authors.lastname: Roberts
authors.forename: C M
authors.initials: CM
authors.lastname: Baker
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002871:Chromosome Banding; D002875:Chromosomes; D005260:Female; D014644:Genetic Variation; D007621:Karyotyping; D008297:Male; D009115:Muridae / Q000235:genetics*