Genetic conflict outweighs heterogametic incompatibility in the mouse hybrid zone?
BACKGROUND
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.


RESULTS
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.


CONCLUSIONS
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.
Macholán
Milos
M
Laboratory of Mammalian Evolutionary Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic , Brno, Czech Republic. macholan@iach.cz
Baird
Stuart J E
SJ
Munclinger
Pavel
P
Dufková
Petra
P
Bímová
Barbora
B
Piálek
Jaroslav
J
D000465:Algorithms; D000483:Alleles; D000818:Animals; D005060:Europe; D005260:Female; D051456:Gene Flow; D005819:Genetic Markers; D049810:Genetic Speciation; D005828:Genetics, Population; D005843:Geography; D006824:Hybridization, Genetic; D016013:Likelihood Functions; D008297:Male; D051379:Mice; D008957:Models, Genetic; D012744:Sex Ratio; D014998:Y Chromosome / Q000235:genetics*
D005819:Genetic Markers