Phylogenomic Analysis of Mitochondrial DNA in Wild Boars and Domestic Pigs in West Siberia and Southeast Asia

The phylogeny among pigs from different regions can contribute important insights into their population history and even adaptation strategy. Geographically, Vietnam links southern China and Southeast Asia, and likewise, Siberia links northern China and Europe, so there might be gene flow among pigs in these regions. However, previously, the evolutionary studies mainly focused on middle and south part of Asia rather than these regions, and also based on very short DNA fragments. Here, we reported whole-mitogenomic analysis of Vietnam pigs and Siberia pigs. We find that Vietnam pigs have very close relationship with pigs in south and north regions of China, while Siberia wild boars has closer relationship with wild boars only from Xinjiang region in China. Interestingly, Siberia domestic pigs are clustered into European pigs. The selective pressure analysis reveals that the selective constraint in Siberia wild boars are more stringent than Vietnam pigs. The results suggest that 1) Vietnam pigs may have more extensive gene flow with other pigs across Asia than Siberia pigs; 2) The purifying selective pressure is not released due to potentially small effective population size, instead, the effect of environment constraint on mitochondrial genes is more obvious in Siberia wild boars than that in Vietnam pigs, contributing to the adaptation of cold environment for Siberia pigs. This study may provide insights into our understanding of the evolution of pigs in Asia.