Origin Of Modern Domestic Dogs

There was very close relationship between human and domestic dogs, comparing with other domestic animals. The domestic dogs were intimate friends and accompanier of human. Dogs were first animal domesticated by man, and originated from gray wolves. The migration of modern domestic dogs printed by the human migration because dogs moved with human after the domestication event happened. However, it was still unknown when and where dogs were domesticated. Meanwhile, there were 330 dog breeds accepted by F.C.I., including Pekingese, Shar Pei, and Tibetan Mastiff originated from China. How did such various breeds selected by hominid? Scientists suggested many scenarios for above issues, and continued their research to find the answers.For the first domesticating places, Vila's paper could be looked as a conclusion of the former research before 1990s. Vila et al suggested "Multiple and Ancient Origins of the Domestic Dog". They said: "Associations of dog haplotypes with other wolf lineages indicated episodes of admixture between wolves and dogs. Repeated genetic exchange between dog and wolf populations may have been an important source of variation for artificial selection". The domestic dogs originated from wolves was established again, while dog's gene pool was not effected by other canids. Vila's result would be wrong for his smaller sample size and coverage in the worldwide.When the twenty-first century coming, Savolainen, our collaborator, suggested the East Asian origin of domestic dogs according to the mitochondria! DNA study. They proved that all dogs, including different dog breeds, originated from a common group after the data set was analyzed using network method on genetic structure. The common origin of dogs indicated that the dog breeds were not generated by wolf domestication in different geography or interbreeding between wolves and dogs. The coalescent time of East Asian origin of domestic dogs was estimated as 15,000 or 40,000 YBP.However, we noticed that the original area, decided by Savolainen et al, was very large from East longitude 75?to 180'. Was it true that the domestic dogs originated in such a large area? Moreover, we found that the sample size in Southwest Asian population was small. We were afraid that Southwest Asia was not included in the original center for its small sample size, because many evidences showed that Southwest Asia was an original center of some modern domestic animals. Savolainen thought that there were at least six founders existing in the origin center, because clade A structure was too complicated to decide how many founders were contained in it. So, we were still unknown the maternal founder number in the origin center. And, how did European and American populations come from? To solve these problems, we continued our study based on Savolainen's work.We enlarged our sample size in East Asia, especially in China, in order to find the original center of domestic dogs in a smaller area. We supposed that China would be a part of the origin center for itsabundant archeological remains and classical literature record. We increased Southwest Asian sample size in order to test how Southwest population effected on the origin center.In our study, the population grouping was tested by AMOVA, and the genetic structure of different dog populations was analyzed by minimum-spanning network. We compared the variance of population genetic structure before and after decreasing the center area, when we started to reduce the center area step by step. Furthermore, the statistic index of genetic diversity and genetic structure was used as secondary analysis, so as to investigate origin center and the population dispersing pathway. At last, we obtained the smallest origin center of domestic dogs. The coalescent time of new origin center was estimated by P value in the center network.We reanalyzed the American ancient DNA reported by Leonard et al in 2002, because we suspected their saying: "(The ancient DNA sequences not appearing in modern domestic dog sequenc...