Study into the genetics of different sized horns

The Universities of Edinburgh and Sheffield have published results of a genetic study into the links between male rams' horn size and their survival rates.

New research into wild sheep living on the Isle of St Kilda in Scotland has revealed that, although large-horned rams win more females, rams with small or medium-sized horns are more likely to live longer.

The scientists also found the gene that controls the horn size – whether small, medium or large – and those with medium-size horns also carry the small horn gene, which they are able to pass on to the next generation.

Medium-horned rams were, interestingly, recorded to have mated almost as successfully as large-horned rams as well as living relatively long lives.

The study involved data spanning over more than two decades and proves that, while physical dominance can give some wild animals the edge over their sexual rivals, weaker competitors have other advantages.

"Until now, we did not fully understand why small horns had not died out," said Dr Susan Johnston, from Edinburgh's School of Biological Sciences, who carried out the study.

"Although it may appear that larger horns are better, we found that the increased survival of medium-horned rams allowed them to catch up with their big-horned rivals in terms of how many offspring they have.

"As they are carriers of the small horn gene and have many offspring, this means that small-horned rams will continue to turn up in the population."

The study has been published in the journal Nature.

Image courtesy of the University of Edinburgh