Molecular phylogenetics relationship between six Chinese native pig breeds and three Swedish pig breeds from mitochondrial DNA.

Mitochondrial DNA genetic polymorphisms were used to evaluate the relationship between 6 Chinese indigenous pig breeds and 3 Swedish domestic pig breeds. A total of 440 bp of the control region and 798 bp of cytochrome b (cyt b) gene of mtDNA were determined from 140 pigs of 9 different breeds. The results of phylogenetics analysis showed that 6 Chinese native pig breeds originated from the Asian wild boar. The pairwise nucleotide sequences divergence suggested that they might occur about 413,000-875,000 years before present (YBP) between Chinese native pig breeds and European wild boar, and approximately 7,500-15,600 YBP between Chinese native pig breeds and Asian wild boar. Three Swedish pig breeds are present both European clade and Asian clade, which is due to the documented introgression of Chinese pig breeds into European domestic pig breeds 2 thousand years ago or during early 18th century.