Mitochondrial DNA Analysis Of Ancient Domestic Goat Excavated From Bancheng And Shuanggucheng Sites, Inner Mongolia, China

The domestic goat (Capra hircus ) is one of the most important livestock species in the history of human society. Because it provides variety of source, such as meat, milk, skin and fiber to human, and has outstanding capabilities to be easy breed and transported, it is wildly known as the"poor man's cow".China has plenty of domestic goat breeds, spread from North to South, and many goat remains have been found in archaeology sites throughout the whole country. But the previous studies of goat genetics, diversity, population history and the origin are always focus on the modern breeds in China. The utility of genetic studies of modern domesticates can be confounded by thousands of years of selective breeding, hybridization and introgression that separate modern domesticates from their progenitors. Ancient DNA has been wildly used to study the genetic structure and the domestication of livestocks such cattle ,horses, dogs, sheep, and pigs. In order to investigate the history for feeding goats in North China, we analyzed 14 ancient goat teeth samples from the archaeology sites of the inner Mongolia area of China. By using the sequences of the mtDNA, we hope to reconstruct the phylogenetic structure of domestic goat 2 500 years ago.The bancheng and shuanggucheng cemeteries are located in liangcheng town in inner Mongolia of China. These sites are all belong to the Archaeological Ensemble of Daihai which have been well studied by archaeologists for their history and relationship. Many kinds of ruminant animal remains such as goat, sheep, cattle, were excavated from these two archaeological sites. 14 mandibles were selected for ancient DNA analysis which have been distinguished to be domestic goat morphologically. we amplified a 289bp mtDNA fragment of the HVI control region because it has been proved informative for tracing the evolution and migration history of human and domestic animals.10 reproducible ancient goat sequences were obtained from 14 samples (three were successfully amplified by sheep primers, one failed). The results reveal that molecular protocols may be a convincing complementarity for the morphological authentication for funerary animals. the Neighbor-joining tree of the ancient samples and the reference haplotypes showed that the ancient haplotypes belong to three divergent haplogroups A , B1 and D which were previously identified. They have much higher mtDNA diversity in control region than the other domestic ruminate animals such as sheep and cattle, and it has already been shown in modern goat breeds. It's may not only result from the multiple maternal origins, but also the sustained transportation among regions and continents.Principal component (PC) map based on the distance matrix of the ancient populations and other 13 goat populations from different countries all over the world shown a closer genetic distance between ancient samples and modern chinese goat populations. A two-dimensional MDS plot was obtained based on the Pairwise FST values between ancient populations and other 18 modern chinese goat populations. It revealed the ancient population was closed to henan, hebei, guizhou, sichuan modern goat populations. The polt also revealed a weak geographical structure of mtDNA variaties in modern Chinese domestic goat breeds.Goat genetic history is likely to be linked to human history of colonization, migration, and commerce. The Daihai area where the archaeology sites locate is really a sensitive region to the temperature and humidity. About 2500 years before, this area was undergoing a transition period from dry-cool to warm-humid, so it's suitable for stock raising. It may be infer from our work that people from this region moving down to southen places that time brought goats, sheep and other livestocks for breeding, and these livestocks have influenced the modern goat population structure. If there is a chance for analyze ancient DNA of goat remains from the archaeological sites along the possible domestic channel, we may infer the origin and expansion of chinses domestic goats.