Data from: House mouse Slx and Sly CNV and expression data

A remarkable gene copy number (CN) arms race system has recently been
described in laboratory mice, where Slx;Slxl1 and Sly genes compete over
transmission by altering fertilisation success of X and Y
chromosome-bearing sperm, respectively. Here, we focus on this system in
nature, where natural selection can counter CN/gene product escalation.
Our model is house mouse subspecies hybridising in Europe. In some
regions, Y chromosomes of the Eastern subspecies have introgressed onto
Western genomic backgrounds, accompanied by sex ratio distortion in favour
of males, consistent with the inbred-lines suggested mechanism:
overabundance of SLY protein expressed by invading Y chromosomes. We take
Slx as representative of the X side of this arms race and measure Slx|Sly
CN and expression across an ‘Invasion’ transect where Ys introgress and a
‘Control’ transect with negligible introgression. Since we found similar
Slx|Sly ratios in both transects, SLY overabundance is unlikely to explain
the introgression. However, Slx CN is relatively low in the introgression
area, suggesting Slx is less able to combat Sly effects here. Further,
deterministic changes in Slx;Sly expression proportions versus CN
proportions suggest standing variation for trans regulation of Slx|Sly is
being co-opted in nature where their arms race reduces population fitness.