Sex ratio distorters (SRDs) are heritable elements that bias offspring sex ratios to enhance their transmission. In the terrestrial isopod Armadillidium vulgare, feminization of genetic males can occur through vertical transmission of the sex ratio distorter known as the f-element, as well as through infection by Wolbachia, a maternally inherited bacterial endosymbiont that can alter host reproduction. We investigated whether associations between sex ratio distorters and mitochondrial haplotypes in U.S. populations differ from those reported in European populations. To address this, we sampled A. vulgare from 12 U.S. states and screened individuals for Wolbachia infection, the presence of the f-element, and mitochondrial COI haplotypes. We found that Wolbachia exhibits a heterogeneous distribution across populations and haplotypes, in contrast to the stronger associations observed in European populations. The f-element occurred at lower overall frequencies but showed a strong association with mitochondrial haplotype VI. These results indicate that patterns associated with SRDs differ from those observed in Europe and are consistent with multiple introductions and population mixing shaping these distributions in U.S. populations.
Kansal et al. (Fri,) studied this question.