Genetic conflict outweighs heterogametic incompatibility in the mouse hybrid zone?
1 Laboratory of Mammalian Evolutionary Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic (ASCR), Brno, Czech Republic
2 Institute of Botany and Zoology, Masaryk University, Brno, Czech Republic
3 INRA, Centre de Biologie et de Gestion des Populations, Campus International de Baillarguet, Montferrier-sur-Lez, France
4 CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Vairão, Portugal
5 Biodiversity Research Group, Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
6 Department of Genetics, University of South Bohemia, Èeské Budìjovice, Czech Republic
7 Department of Population Biology, Institute of Vertebrate Biology, ASCR, Studenec, Czech Republic
BMC Evolutionary Biology 2008, 8:271 doi:10.1186/1471-2148-8-271Published: 3 October 2008
The Mus musculus musculus/M. m. domesticus contact zone in Europe is characterised by sharp frequency discontinuities for sex chromosome markers at the centre of wider clines in allozyme frequencies.
We identify a triangular area (approximately 330 km2) where the musculus Y chromosome introgresses across this front for up to 22 km into domesticus territory. Introgression of the Y chromosome is accompanied by a perturbation of the census sex ratio: the sex ratio is significantly female biased in musculus localities and domesticus localities lacking Y chromosome introgression. In contrast, where the musculus Y is detected in domesticus localities, the sex ratio is close to parity, and significantly different from both classes of female biased localities. The geographic position of an abrupt cline in an X chromosome marker, and autosomal clines centred on the same position, seem unaffected by the musculus Y introgression.
We conclude that sex ratio distortion is playing a role in the geographic separation of speciation genes in this section of the mouse hybrid zone. We suggest that clines for genes involved in sex-ratio distortion have escaped from the centre of the mouse hybrid zone, causing a decay in the barrier to gene flow between the two house mouse taxa.