Chromosomal speciation of humans and chimpanzees revisited: studies of DNA divergence within inverted regionsSzamalek J.M. · Cooper D.N. · Hoegel J. · Hameister H. · Kehrer-Sawatzki H.
aDepartment of Human Genetics, University of Ulm, Ulm (Germany) bInstitute of Medical Genetics, Cardiff University, Cardiff (UK)
The human and chimpanzee karyotypes are distinguishable in terms of nine pericentric inversions. According to the recombination suppression model of speciation, these inversions could have promoted the process of parapatric speciation between hominoid populations ancestral to chimpanzees and humans. Were recombination suppression to have occurred in inversion heterozygotes, gene flow would have been reduced, resulting in the accumulation of genetic incompatibilities leading to reproductive isolation and eventual speciation. In an attempt to detect the molecular signature of such events, the sequence divergence of non-coding DNA was compared between humans and chimpanzees. Precise knowledge of the locations of the inversion breakpoints permitted accurate discrimination between inverted and non-inverted regions. Contrary to the predictions of the recombination suppression model, sequence divergence was found to be lower in inverted chromosomal regions as compared to non-inverted regions, albeit with borderline statistical significance. Thus, no signature of recombination suppression resulting from inversion heterozygosity appears to be detectable by analysis of extant human and chimpanzee non-coding DNA. The precise delineation of the inversion breakpoints may nevertheless still prove helpful in identifying potential speciation-relevant genes within the inverted regions.
Request reprints from Dr. Hildegard Kehrer-Sawatzki
Department of Human Genetics, University of Ulm
Albert-Einstein-Allee 11, 89081 Ulm (Germany)
telephone: +49 731 5002 3416; fax: +49 731 5002 3438
The research was funded by the Deutsche Forschungsgemeinschaft (DFG KE 724/2–1).
Manuscript received: 17 July 2006
Accepted in revised form for publication by M. Schmid,: 10 August 2006.
Number of Print Pages : 8
Number of Figures : 1, Number of Tables : 3, Number of References : 45
Cytogenetic and Genome Research
Vol. 116, No. 1-2, Year 2007 (Cover Date: January 2007)
Journal Editor: Schmid, M. (Würzburg)
ISSN: 1424–8581 (print), 1424–859X (Online)
For additional information: http://www.karger.com/CGR