Data from: Contrasting patterns of X-chromosome divergence underlie multiple sex-ratio polymorphisms in stalk-eyed flies

Sex-linked segregation distorters cause offspring sex ratios to differ
from equality. Theory predicts that such selfish alleles may either go to
fixation and cause extinction, reach a stable polymorphism, or initiate an
evolutionary arms race with genetic modifiers. The extent to which a sex
ratio distorter follows any of these trajectories in nature is poorly
known. Here we used X-linked sequence and simple tandem repeat data for
three sympatric species of stalk-eyed flies (Teleopsis whitei and two
cryptic species of T. dalmanni) to infer the evolution of distorting X
chromosomes. By screening large numbers of field and recently lab-bred
flies we found no evidence of males with strongly female-biased sex ratio
phenotypes (SR) in one species but high frequencies of SR males in the
other two species. In the two species with SR males, we find contrasting
patterns of X chromosome evolution. T. dalmanni - 1 shows chromosome-wide
differences between sex-ratio (XSR) and standard (XST) X chromosomes
consistent with a relatively old sex-ratio haplotype based on evidence
including genetic divergence, an inversion polymorphism, and reduced
recombination among XSR chromosomes relative to XST chromosomes. In
contrast, we found no evidence of genetic divergence on the X between
males with female-biased and non-biased sex ratios in T. whitei. Taken
with previous studies that found evidence of genetic suppression of sex
ratio distortion in this clade, our results illustrate that sex ratio
modification in these flies is undergoing recurrent evolution with diverse
genomic consequences.