Genome-wide detection of copy number variations in polled yak using the Illumina BovineHD BeadChip.

Background: Copy number variations (CNVs), which are genetic variations present throughout mammalian genomes, are a vital source of phenotypic variation that can lead to the development of unique traits. In this study we used the Illunima BovineHD BeadChip to conduct genome-wide detection of CNVs in 215 polled yaks.

Results: A total of 1066 CNV regions (CNVRs) were detected with a total length of 181.6 Mb, comprising ~ 7.2% of the bovine autosomal genome. The size of these CNVRs ranged from 5.53 kb to 1148.45 kb, with an average size of 170.31 kb. Eight out of nine randomly chosen CNVRs were successfully validated by qPCR. A functional enrichment analysis of the CNVR-associated genes indicated their relationship to a number of molecular adaptations that enable yaks to thrive at high altitudes. One third of the detected CNVRs were mapped to QTLs associated with six classes of economically important traits, indicating that these CNVRs may play an important role in variations of these traits.

Conclusions: Our genome-wide yak CNV map may thus provide valuable insights into both the molecular mechanisms of high altitude adaptation and the potential genomic basis of economically important traits in yak.