Using singleton densities to detect recent selection in Bos taurus

Many quantitative traits are subject to polygenic selection, where several genomic regions undergo small, simultaneous changes in allele frequency that collectively alter a phenotype. The widespread availability of genome data, along with novel statistical techniques, has made it easier to detect these changes. We apply one such method, the ‘Singleton Density Score’, to the Holstein breed of Bos taurus to detect recent selection (arising up to around 740 years ago). We identify several genes as candidates for targets of recent selection, including some relating to cell regulation, catabolic processes, neural-cell adhesion and immunity. We do not find strong evidence that three traits that are important to humans – milk protein content, milk fat content, and stature ­– have been subject to directional selection. Simulations demonstrate that since B. taurus recently experienced a population bottleneck, singleton numbers are reduced limiting the power of SDS methods. These results inform o...