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.
Laboratory of Mammalian Evolutionary Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic , Brno, Czech Republic. macholan@iach.cz
Milos
M
Macholán
Stuart J E
SJ
Baird
Pavel
P
Munclinger
Petra
P
Dufková
Barbora
B
Bímová
Jaroslav
J
Piálek
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