Selection signature analysis reveals RDH5 performed key function in vision during sheep domestication process

Area of Science:

• Genomics
• Animal Genetics
• Evolutionary Biology

Background:

• Sheep (Ovis aries) are a successful domesticated species with significant phenotypic changes since the Neolithic age.
• The genetic basis for these variations during domestication remains largely unknown.
• Understanding these genetic changes can shed light on animal evolution and adaptation.

Purpose of the Study:

• To investigate the genetic differences between Asiatic mouflon wild sheep (Ovis orientalis) and domesticated Hu sheep (Ovis aries).
• To identify genes under positive selection during sheep domestication.
• To explore the role of specific genes, such as RDH5, in phenotypic variations and domestication.

Main Methods:

• Whole genome resequencing was employed to compare the genomes of wild and domesticated sheep.
• Bioinformatic analyses were used to identify positively selected genes and detect genetic mutations.
• Functional analysis was performed to assess the impact of identified mutations on gene activity.

Main Results:

• 755 genes were identified as being under positive selection during domestication.
• Genes associated with sensory perception, including OPRL1, LEF1, TAS1R3, ATF6, VSX2, MYO1A, and RDH5, showed directional evolution.
• A specific missense mutation (c.T722C/p.M241T) in the RDH5 gene was found, with the T allele fixed in Hu sheep, reducing retinol dehydrogenase activity and potentially affecting vision.

Conclusions:

• Sheep domestication involved significant positive selection for genes related to sensory perception development.
• The RDH5 gene and its variants are implicated in retinal degeneration in sheep.
• The identified mutation in RDH5 may have been selectively advantageous, driven by both natural and artificial selection pressures during domestication.