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

Macholán M, Baird SJ, Munclinger P, Dufková P, Bímová B, Piálek J - BMC Evol. Biol. (2008)

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Mammalian Evolutionary Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic , Brno, Czech Republic. macholan@iach.cz

ABSTRACT

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.

Conclusion: 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.

Show MeSH

Related in: MedlinePlus

Likelihood (support) profiles for monotonic change in allele frequencies. The profiles show likelihood of monotonic change of individual markers from M. m. musculus to M. m. domesticus, moving through the field area following a compass bearing in a 90° range including due west (W) and northwest (NW). Yellow: Gpd1; pink: Abpa; red: Btk (X chromosome); brown: Mpi; orange: Idh1; purple: Es1; dark blue:Sod1; green: Np; blue: Y chromosome; bold black: consensus support over all loci. For clarity of presentation the profiles are smoothed over a window of 3°. Since the smoothing removes precise details around the maxima these may not correspond precisely to Table 1 which is based on the original (unsmoothed) profiles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2576241&req=5

Figure 3: Likelihood (support) profiles for monotonic change in allele frequencies. The profiles show likelihood of monotonic change of individual markers from M. m. musculus to M. m. domesticus, moving through the field area following a compass bearing in a 90° range including due west (W) and northwest (NW). Yellow: Gpd1; pink: Abpa; red: Btk (X chromosome); brown: Mpi; orange: Idh1; purple: Es1; dark blue:Sod1; green: Np; blue: Y chromosome; bold black: consensus support over all loci. For clarity of presentation the profiles are smoothed over a window of 3°. Since the smoothing removes precise details around the maxima these may not correspond precisely to Table 1 which is based on the original (unsmoothed) profiles.

Mentions: Frequencies of musculus alleles at the Btk locus at all the sampling sites under study are depicted as pie diagrams in Figure 2a. The transition of this X-chromosome marker from the domesticus to the musculus side is rather abrupt and the position and orientation of its front is very similar to the position and orientation of a consensus over autosomal loci [14]. On the other hand, the spatial distribution of Y chromosome frequencies is very different from that of other markers (Figure 2b). Figure 3 shows log likelihood (support) profiles for monotonic change in allele frequencies from musculus-like to domesticus-like, moving through the field area following a compass bearing lying within a 90° range including due west (W) and northwest (NW). The Y chromosome is a clear outlier, its most likely change being oriented roughly 45° clockwise of the other loci. Summing log likelihood profiles over all loci produces a consensus profile (in bold black in Figure 3) under the assumption that the orientation of change in allele frequencies is the same for all the loci.


Genetic conflict outweighs heterogametic incompatibility in the mouse hybrid zone?

Macholán M, Baird SJ, Munclinger P, Dufková P, Bímová B, Piálek J - BMC Evol. Biol. (2008)

Likelihood (support) profiles for monotonic change in allele frequencies. The profiles show likelihood of monotonic change of individual markers from M. m. musculus to M. m. domesticus, moving through the field area following a compass bearing in a 90° range including due west (W) and northwest (NW). Yellow: Gpd1; pink: Abpa; red: Btk (X chromosome); brown: Mpi; orange: Idh1; purple: Es1; dark blue:Sod1; green: Np; blue: Y chromosome; bold black: consensus support over all loci. For clarity of presentation the profiles are smoothed over a window of 3°. Since the smoothing removes precise details around the maxima these may not correspond precisely to Table 1 which is based on the original (unsmoothed) profiles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2576241&req=5

Figure 3: Likelihood (support) profiles for monotonic change in allele frequencies. The profiles show likelihood of monotonic change of individual markers from M. m. musculus to M. m. domesticus, moving through the field area following a compass bearing in a 90° range including due west (W) and northwest (NW). Yellow: Gpd1; pink: Abpa; red: Btk (X chromosome); brown: Mpi; orange: Idh1; purple: Es1; dark blue:Sod1; green: Np; blue: Y chromosome; bold black: consensus support over all loci. For clarity of presentation the profiles are smoothed over a window of 3°. Since the smoothing removes precise details around the maxima these may not correspond precisely to Table 1 which is based on the original (unsmoothed) profiles.
Mentions: Frequencies of musculus alleles at the Btk locus at all the sampling sites under study are depicted as pie diagrams in Figure 2a. The transition of this X-chromosome marker from the domesticus to the musculus side is rather abrupt and the position and orientation of its front is very similar to the position and orientation of a consensus over autosomal loci [14]. On the other hand, the spatial distribution of Y chromosome frequencies is very different from that of other markers (Figure 2b). Figure 3 shows log likelihood (support) profiles for monotonic change in allele frequencies from musculus-like to domesticus-like, moving through the field area following a compass bearing lying within a 90° range including due west (W) and northwest (NW). The Y chromosome is a clear outlier, its most likely change being oriented roughly 45° clockwise of the other loci. Summing log likelihood profiles over all loci produces a consensus profile (in bold black in Figure 3) under the assumption that the orientation of change in allele frequencies is the same for all the loci.

Bottom Line: 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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratory of Mammalian Evolutionary Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic , Brno, Czech Republic. macholan@iach.cz

ABSTRACT

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.

Conclusion: 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.

Show MeSH
Related in: MedlinePlus