Comet the bull, a historical genome from the agricultural revolution
During the 18th century, new breeding practices reformed English farming, producing the Shorthorn breed, which grew to dominate English cattle herds. Comet (born 1804) was an early Shorthorn bull with such influence that he is referred to as the “Adam” of the breed. He famously sold for 1,000 guineas and his breeding influenced Sewall Wright in developing population genetic theory. From a curated tooth we sequenced Comet's genome to high coverage (15.4X) and co-analysed it with published cattle genomes to assess his legacy on modern cattle. Almost half of Comet's genome consists of runs of homozygosity, validating his recorded pedigree and confirming the practice of extreme and deliberate in-and-in breeding at the inception of modern breeding. Despite the ~40 generations separating Comet from present-day Shorthorns, over half (58%) of his genome, identifiable through identity by descent segments, segregates in the present-day breed. Shorthorn were internationally influential and he also shares IBD with 17 other breeds included in our analysis. The genome regions that were transmitted to descendants with higher frequency harbour genes known to influence milk and meat production, immune system function, and male fertility; Comet's genomic heritage may be associated with production traits selected for in the intervening centuries.
During the 18th century, new breeding practices reformed English farming, producing the Shorthorn breed, which grew to dominate English cattle herds. Comet (born 1804) was an early Shorthorn bull with such influence that he is referred to as the “Adam” of the breed. He famously sold for 1,000 guineas and his breeding influenced Sewall Wright in developing population genetic theory. From a curated tooth we sequenced Comet's genome to high coverage (15.4X) and co-analysed it with published cattle genomes to assess his legacy on modern cattle. Almost half of Comet's genome consists of runs of homozygosity, validating his recorded pedigree and confirming the practice of extreme and deliberate in-and-in breeding at the inception of modern breeding. Despite the ~40 generations separating Comet from present-day Shorthorns, over half (58%) of his genome, identifiable through identity by descent segments, segregates in the present-day breed. Shorthorn were internationally influential and he also shares IBD with 17 other breeds included in our analysis. The genome regions that were transmitted to descendants with higher frequency harbour genes known to influence milk and meat production, immune system function, and male fertility; Comet's genomic heritage may be associated with production traits selected for in the intervening centuries.
Trinity College Dublin