Phylogeography Of Wild Boar (Sus Scrofa) And The Origin Of Domestic Pigs Based On Mitochondrional Variation Analysis

The wild boar (Sus scrofa), which inhabited wide areas of Asia, Europe, and North Africa, is an ancestral species of domestic pigs. In this paper, a review of phylogeography was given, the phylogeography of the wild boar in the Northeast of Asia and the origin of domestic pigs were discussed based on the analysis of mitochonndrial D-loop region and cytochrombe b (cyt b) sequence variation.1. In the review, the periodical oscillations of Global climate during the Pleistocene and the change of environments in China were introduced; the basic theory and the development of phylogeography were also summarized.2. The mitochondrial D-loop from 72 wild boars in the northeast, north and Szechwan of China were determined, and another 72 sequence of Japanese wild boars and Ryukyu wild boars were got from GenBank. Total of 1044 aligned sites were obtained, including 42 polymorphic sites. The phylogenetic relationship indicates that the wild boars in the Northeast of Asia share a common ancestor. The Japanese wild boars were more closely related to Northeast China wild boars than the others, and the Ryukyu wild boars have a closer relationship with the Northern China wild boars. Nested contingency analysis of geographical associations and the nested cladistic analysis of geographical distance for the mtDNA haplotypes of control region indicate that there are significant geographical population structure in wild boars of Northeast Asia. The ancestral population had experienced a long distance movement to form the contemporary population. The results also suggest that (i) the Ryukyu wild boar population may descendant from the continental boar, and it have experienced theallopatric fragmentation in the past; (ii) the Japanese wild boar population may descendant from the Northeast China wild boar; (iii) the Northern China wild boar population in the southern areas have a higher genetic diversity than that in the northern areas, and the population have experienced the contiguous range expansions.3. Total of 238 sequence of mitochondrial cyt b was analyzed, among which 72 were from Chinese wild boar. Seventy-four haplotypes, 77 Singleton polymorphic sites and 51 Parsimony informative polymorphic sites were found in the study. The results indicated: (1) there is closer relationship between Ussurian China wild boar and South China wild boar. Ussurian China wild boar population may descendant from the South China wild boar with a long distance colonization. (2) Korea wild boar was not the transitional population of Japanese wild boar and Ussurian China wild boar, and Korea was not the corridor of the Ussurian China wild boar pass to Japan islands. (3) Italy was a refugium of European wild boar in ice age, but this population has been restricted in the peninsula by the Alps. Europe wild boar was likely expanded from Asia Minor or Balkan Peninsula.4. Total of 340 cyt b sequence were used to discuss the origin of the domestic pig, of which 238 were from wild boars of the world, and 102 were from the domestic pigs. 156 variable sites were found and 108 haplotypes were defined. The results indicated: (1) the pigs were domesticated in Europe and Asia independently, and there is introgression between Europe and Asia domestic pig. (2) The ancestor of Europe domestic pigs is the Europe wild boar. (3) There is a common domestic center for Asia domestic pigs, and South China wild boar is the ancestor of them. Chinese domestic pigs and European domestic pigs may affect the formation of Korean domestic pigs.