Sexual selection can partly explain low frequencies of Segregation Distorter alleles

The ( ) allele found in distorts Mendelian inheritance in heterozygous males by causing developmental failure of non- spermatids, such that greater than 90% of the surviving sperm carry . This within-individual advantage should cause to fix, and yet is typically rare in wild populations. Here, we explore whether this paradox can be resolved by sexual selection, by testing if males carrying three different variants of suffer reduced pre- or post-copulatory reproductive success. We find that males carrying the allele are just as successful at securing matings as control males, but that one variant ( ) reduces sperm competitive ability and increases the likelihood of female remating. We then used these results to inform a theoretical model; we found that sexual selection could limit to natural frequencies when sperm competitive ability and female remating rate equalled the values observed for . However, sexual selection was unable to explain natural frequencies of the allele when the model was parameterized with the values found for two other variants, indicating that sexual selection alone is unlikely to explain the rarity of .