Mechanisms of chromosomal change, distribution patterns, extent of genotypic, phenotypic and ecological divergence, and nature and degree of reproductive isolation were reviewed in 10 chromosomally variable southern African rodent species and species complexes. Genetically similar peripatric or parapatric chromosome races freely interbreed (striped mice, Rhabdomys pumilio; vlei rats, Otomys irroratus), while genotypically or phenotypically divergent, sympatric sibling species (multimammate mice, Mastomys natalensis–M. coucha; tree rats, Thallomys paedulcus–T. nigricauda; red veld rats, Aethomys chrysophilus–A. ineptus) appear reproductively isolated, suggesting a correlation between genetic distance and onset of reproductive isolation. The allopatric gerbil species pair, Tatera brantsii–T. afra, shows little or no prezygotic reproductive isolation despite well-developed male-biased postzygotic isolation (i.e., Haldane effect) that may be associated with a rearrangement on the Y chromosome. Within the actively speciating vlei rat, Otomys irroratus, complex, despite widespread laboratory interbreeding between chromosome races, postzygotic isolation (virtual hybrid sterility) was demonstrated due to fixation of a tandem fusion rearrangement in the high-altitude (>1,400 m) A1 race. Both post- and prezygotic isolation have developed in the absence of significant measurable genotypic divergence at either the gene or the DNA level. Acquisition of reproductive isolation and incipient speciation in the vlei rat complex appears to be mediated by both chromosomal (postzygotic) and nonchromosomal (prezygotic) processes.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.