Horn type and horn length genes map to the same chromosomal region in Soay sheep

S. E. Johnston, D. Beraldi, A. F. McRae, J. M. Pemberton, J. Slate

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The evolution of male weaponry in animals is driven by sexual selection, which is predicted to reduce the genetic variability underlying such traits. Soay sheep have an inherited polymorphism for horn type in both sexes, with males presenting with either large, normal horns or small, deformed horns (scurs). In addition, there is additive genetic variation in horn length among males with normal horns. Given that scurred males cannot win conflicts with normal-horned males, it is unusual that genes conferring scurs should persist in the population. Identifying the genetic basis of these traits should help us in understanding their evolution. We developed microsatellite markers in a targeted region of the Soay sheep genome and refined the location of the Horns locus (Ho) to a similar to 7.4cM interval on chromosome 10 (LOD-8.78). We then located quantitative trait loci spanning a 34 cM interval with a peak centred close to Ho, which explained the majority of the genetic variation for horn length and base circumference in normal-horned males (LOD=2.51 and LOD=1.04, respectively). Therefore, the genetic variation in both horn type and horn length is attributable to the same chromosomal region. Understanding the maintenance of horn type and length variation will require an investigation of selection on genotypes that (co)determine both traits. 

Original languageEnglish
Pages (from-to)196-205
Number of pages10
Issue number2
Early online date19 Aug 2009
Publication statusPublished - 28 Feb 2010

Keywords / Materials (for Non-textual outputs)

  • quantitative trait locus mapping
  • horn morphology
  • natural population
  • genetic correlation
  • sexual selection
  • trade-off


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