Exploring the Structure of Haplotype Blocks and Genetic Diversity in Chinese Indigenous Pig Populations for Conservation Purpose

Chinese indigenous pigs in the Taihu Lake region are well known for their high fecundity and other excellent characteristics. To better understand the characteristics of these breeds in this area as well as to provide the government and breeders the molecular basis for formulating a reasonable conservation policy, we explored the structure of haplotype blocks and genetic diversity of the 7 populations which is relevant for the management and conservation of these important genetic resources using next-generation sequencing data. In this study, a total of 131 300 single-nucleotide polymorphisms with minor allele frequencies >= 0.05 were obtained for further analysis. In general, there are similar within-breed genetic diversities (He, Ho, P-n, A(r)) among these 7 pig populations in the Taihu Lake region. Average values for the inbreeding coefficients estimates in the 7 populations are 0.110 (F1), 0.056 (F2), and 0.078 (F3). All the breeds have seen a continuous decline in Ne estimates over time with FJ and SW populations having a very similar curve. Moreover, the Ne of SMS pig breeds were smaller than other Chinese pig breeds, indicating that SMS pig breeds underwent stronger selection pressure than other Chinese pig breeds. The average genetic distances among the 7 populations in the Taihu Lake region were 0.235 (MMS), 0.240 (SMS), 0.269 (EH), 0.248 (MI), 0.221 (FJ), 0.254 (JX), and 0.212 (SW). A summary of the number of haplotype blocks and haplotype diversity was also presented. This study provide a deep understanding of the current situation of conservation in this region, thereby uncovering the pertinent insight to better formulate more reasonable preservation policies for the government departments and breeding planners to follow-up.