Wild Soay sheep rams with large horns have more offspring, yet there is considerable genetic variation at RXFP2, a locus strongly implicated in horn size (with different alleles conferring either large or small horns); this study finds that although the larger horn allele leads to more offspring, the smaller horn allele leads to increased survival, meaning heterozygous rams (which develop medium-sized horns) have high reproductive success and survival, providing a rare example of heterozygote advantage.
- Susan E. Johnston
- Jacob Gratten
- Jon Slate
