Comprehensive genomic analysis and selection signature detection in endangered Beigang pigs using whole-genome sequencing data

Abstract

The Beigang pig was recently identified as one of the endangered breeds during a Chinese indigenous pig genetic resource survey. The Beigang breed is notable for its remarkable roughage tolerance and high reproductive capacity according to historical records. Morphologically, the Beigang pig resembles many indigenous pigs in eastern China, especially in its large ears. This makes the Beigang pig a valuable reference for studying the genetic mechanisms on large ear size in pigs. However, there is currently a lack of clear understanding regarding the genetic structure and inbreeding levels of the Beigang pig population. This study used whole-genome sequencing data from Beigang pig (N = 145 pigs) and integrated genetic information from commercial pigs and indigenous pigs in eastern China to conduct a comprehensive analysis of the Beigang pig's genetic structure. Three selection signal detection methods—runs of homozygosity, fixation index, and integrated haplotype score—were employed to explore the differences in genomic selection signatures between Beigang pig and other pig populations. Additionally, we used a public project for regulatory variants discovery and molecular phenotype prediction in farm animal species called FarmGtex to explore the expression of three genes (WIF1, LEMD3, and MSRB3) related to ear size in Beigang pig. This research identified five homozygous variant sites in the WIF1 gene as important candidate loci potentially influencing ear size in Beigang pig. The results indicate that the Beigang pig holds a unique status among Chinese indigenous pigs, characterized by high genetic diversity and low levels of inbreeding. The study also revealed that WIF1 may play a significant role in influencing ear size in this breed. These findings contribute to a deeper understanding of the population structure and genetic characteristics of Beigang pig.