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- Title
A new cytotype of the African pygmy mouse Mus minutoides in Eastern Africa. Implications for the evolution of sex-autosome translocations.
- Authors
Veyrunes, F.; Perez, J.; Borremans, B.; Gryseels, S.; Richards, L.; Duran, A.; Chevret, P.; Robinson, T.; Britton-Davidian, J.
- Abstract
The African pygmy mice (genus Mus, subgenus Nannomys) are recognized for their highly conserved morphology but extensive chromosomal diversity, particularly involving sex-autosome translocations, one of the rarest chromosomal rearrangements among mammals. It has been shown that in the absence of unambiguous diagnostic morphological traits, sex-autosome translocations offer accurate taxonomic markers. For example, in Mus minutoides, irrespective of the diploid number (which ranges from 2n = 18 to 34), all specimens possess the sex-autosome translocations (X.1) and (Y.1) that are unique to this species. In this study, we describe a new cytotype that challenges this view. Males are characterized by the translocation (Y.1) only, while females carry no sex-autosome translocation, the X chromosome being acrocentric. Hence, although sex-autosome translocations (X.1) and (Y.1) are still diagnostic when one or both are present, their absence does not rule out M. minutoides. This cytotype has a large distribution, with specimens found in Tanzania and in the eastern part of South Africa. The nonpervasive distribution of Rb(X.1) provides an opportunity to investigate different evolutionary scenarios of sex-autosome translocations using a phylogenetic framework and the distribution of telomeric repeats. The results tend to support a scenario involving a reversal event, i.e., fusion then fission of Rb(X.1), and highlighted the existence of a new XXXX/XXY sex chromosome system, confirming the remarkable diversity of neo-sex chromosomes and sex determination systems in the African pygmy mice.
- Subjects
EASTERN Africa; MUS minutoides; BIOLOGICAL evolution; ANIMAL introduction; SEX chromosomes; CHROMOSOMAL rearrangement
- Publication
Chromosome Research, 2014, Vol 22, Issue 4, p533
- ISSN
0967-3849
- Publication type
Article
- DOI
10.1007/s10577-014-9440-x