Analysis of genetic diversity and selection signatures on the Zhashi Brown goat through whole genome sequencing data

Abstract

The Zhashi Brown goat is native to Hengyang Municipality in Hunan Province in southern China and boasts a rich history. The goats exhibit exceptional traits, including heat and insect resistance, strong reproductive capabilities and superior meat production. Despite these merits, the currently limited population requires immediate conservation endeavors. In this study, we conducted whole-genome resequencing on 21 Zhashi Brown goats. Additionally, we performed a joint analysis using published whole-genome data from 119 goats, including Chengdu Brown goat, Matou goat, Wuxue goat, Xiangdong Black goat, Qaidam Cashmere goat, Ujumqin Cashmere goat and Shanbei Cashmere goat. The results revealed that the Zhashi Brown goat is genetically more pure than other Southern Chinese goat breeds. Furthermore, the genetic diversity (nucleotide diversity, linkage disequilibrium, runs of homozygosity and inbreeding coefficient) of the Zhashi Brown goat's genome is at a low level among the eight breeds, indicating the need for further conservation. Employing analytical methodologies such as composite likelihood ratio, nucleotide diversity, integrated haplotype score, the fixation index and cross-population extended haplotype homozygosity, we systematically scanned selective signals within the genomic landscape of Zhashi Brown goat. The outcomes underscore strong selection signals associated with genes implicated in immune response, heat tolerance, reproductive performance and meat quality. These findings make a significant contribution to our understanding of the genetics framework associated with adaptive traits in Zhashi Brown goat. Furthermore, this study explores the genetic diversity of the Zhashi Brown goat, which may contribute to the theoretical framework for conserving its genetic resources, while the identified trait-associated variations could inform future strategies to optimize selective breeding programs.