Genetic and Phenotypic Variability in Sheep
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This photo depicts a Gene Network Involving RXFP2, a gene associated with horn development. It interacts with other a number of proteins involved with cell signaling and growth. Horn status is not usually determined by a single gene, it's part of a much larger biological pathway.
Sheep exhibit incredible diversity across breeds ranging from the genetic variables in wool texture and color, horn growth, and tail morphology. These traits have come to be due to hundreds of years of natural variation, geographic adaption, and thousands of years of selective breeding by humans.
Co-Evolution With Humans
Historical Timeline of Human-Sheep Coevolution
"From the Fertile Crescent to Modern Genomic Breeding"
Sheep population from the United Kingdom with different horn patterns
Artifical Selection and Evolutionary Pressures
Artificial selection, the process of human-directed breeding for desired traits has played a significant role in shaping the modern domestic sheep.
Studies of genomic selection (DNA to predict breeding values) are used in sheep production to enhance genetic gain
QTL mapping (Quantitative Trait Loci) is used to identify specific chromosomal regions linked to various traits such as wool and disease resistance.
By comparing genetic markers (M1 and M2) across the parent lines and offspring, researchers are able to find genes or gene clusters that contribute to variability in these traits. In sheep, QTL studies have aided in pinpointing regions linked to the RXFP2 gene (horn) and keratin associated proteins (wool).
The diagram depicts a generational breeding strategy used to fix desirable traits in the sheep population.
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