| The dissertation mainly includes two parts: one is the application of themethods of biostatistics and bioinformation in the research of ancient DNA,the other is mitochondrial DNA polymorphism analysis and genetic structureanalysis of Khitan population.With the rapid development of the biotechnology, the sequences ofMacro Biomolecular tempestuously increase, including the sequences ofancient DNA. Basing on these sequences, we can deduce the information ofevolution, such as the evolutional process, the evolutional impetus, thedevelopmental mechanism, the evolutional velocity, and the evolutional trendof lives, and the forming, the annihilation, and the origin of adaptation ofspecies.DNA from ancient materials and fossil is every helpful to understand theevolutional process. However it is only primary to extract DNA from ancientmaterials for ancient DNA research, how to deal with the sequences is everyimportant. The methods of biostatistics and phylogenetic analysis are thefundamental means of DNA sequences analysis. Basing on these methods, wecan calculate the nucleotide polymorphism, reconstruct the phylogenetic trees,deduce the model of population spread and dynamic trends, deduce the originof the population and the time of divergence, estimate the evolutional velocityand admixture of gene, and discriminate ancient DNA sequences from currentDNA sequences. Moreover, these methods can give the statistic result.Phylogenetic analysis can study the evolutional discipline of population on themolecular level, and it can express these results in the intuitionistic and visualway. Through the phylogenetic analysis of ancient DNA, the phylogeny basedon morphology and immunology can be amended. The phylogeny of manyspecies only based on modern DNA can be amended by the combination ofancient DNA sequences and modern DNA sequences.The application of methods of biostatistics and the means ofphylogenetic analysis in the study of ancient DNA includes: the choice ofsequence in the study, primary sequence alignment, estimating geneticdistance, reconstruction of phylogenetic tree, multidimensional analysis ofgenetic structure, component factor analysis of genetic structure, mediannetwork analysis, estimating the molecular clock and the time of divergence,deduce ancestral sequences, calculating admixture of gene, discriminatingancient DNA sequences, nucleotide mismatch distribution analysis, neutralitytest, and analysis of molecular variance. This paper expatiate the basalprinciple of these methods and the application of these methods in the ancientDNA research. According to the character of ancient DNA, the dissertationdiscusses the strongpoint and shortcoming of these methods, and how to usethese methods, and which method is the best. And these estimations are veryimportant to the disposal of ancient DNA sequence.Khitan ever founded one powerful kingdom in the Eurasian plain, and itgreatly influenced on circumjacent population. And the place that Khitan everlived is the zone that meadow culture and agriculture culture of china collidedand amalgamated, and also is the zone for intercourse of the populations in themeadow intercourse. Therefore, it is significant to study the genetic structure,gene communication of these populations.Basing on the means of molecular biology, this paper studies the geneticstructure of Khitan population by ancient DNA. In this paper, we take theapplication of biostatistics and evaluation as main body, and take the analysisprocess of the DNA sequence of Khitan population as examples. According tothese strucutre,the paper expatiates the foundational principle, basal methods,application, and the setting of interrelated parameter of the biostatistics in theancient DNA research.For the experiments molecular biology, the skeletons of human remainswere collected from the necropolises of Xiaohe's family, Yelv yuzhi's familyand shanzuizi, as well as the tombs of Shangdu, Jianshan and Turki. The HVRI of mtDNA in these skeletons was extracted amplified, sequenced. Geneticanalysis of the Khitan population in Liao dynasty has been done on four topicsof genetic structure, race, origin and descendent.The sequences of individuals in the Khitan population were analyzed.The analyses on the mutated site mutated rate, haplogroup of individuals'sequences show that the Khitan population was close to Asia populations.Besides, the researches on the relationships in Khitan population indicate thatthe samples from necropolis of Xiaohe's family were closely related to thatfrom Shangdu tombs. In the same way, the samples from necropolis ofYelvyuzhi's family were closely related to that of Turki tomb. And thesamples from Shanzuizi necropolis were closely related to that from Jianshantomb. The samples of different tombs were classed into noble and plebeian,early phase and middle-late phase or east and west. It seems that the geneticdifferences between noble and plebeian or between early phase andmiddle-late phase were remarkable. It probably attribute to the policy ofintermarriage between Yelv and Xiao and the gene flow from otherpopulations. However there wasn't much difference between the east and thewest population of Khitan. Mismatch distributions were computed and theunimodal distributions were interpreted as signs of demographic expansions.In parallel, the raggedness index was generally lower than 0.05, negativevalues of Fu's Fs and Tajima's D that differ significantly from zero, alsosupported these patterns of demographic history.We also researched on the samples of Yelv yuzhi's family and Xiaohe'sfamily in this paper. The results indicated that the genetic structure of Yelvyuzhi's family is every similar to that of Xiaohe's family, but they are not thesame. The comparability of genetic structure may be coming from theirmarriage, and the difference may be form the data they lived. And theseresults indicate the special marital system of Khitan population.To confirm the ethnic group of Khitan, twenty-two modern contrastedpopulations in North Asia, East Asia, and Central Asia were chosen. The resultof multidimensional analysis shows that Khitan population was more closelyrelated to populations in North Asia than to that in East Asia or Centeral Asia.There was some argument that Khitan came from Xianbei or Xiongnu.One of the purposes in this paper was to confirm the origin of Khitan. Wecontrasted Khitan population with Xianbei, Xiongnu and all of the eightmodern populations. The results of phylogenetic and multidimensionalanalysis show that the genetic relationship between Khitan and Xianbei wasthe closest. However, the genetic relationship between Xiongnu and somemodern North Asia populations, such as Outer Mongolia, Inner Mongolia,Buryat etc., was closer than that between Xiongnu and Xianbei, or Xiongnuand Khitan. Above-mentioned conclusions support that Khitan origined fromXianbei and indicate that there was no original relationship between Xiongnuand Khitan at the same time.Arguments focus on the Khitan's descendants now. We discussed thisquestion by using molecular methods based on the archaeology, history andethnology literatures. The results show that most of Khitans were assimilatedby Mongolians after the fall of Liao dynasty. The direct descendant of Khitanhas not been found in modern populations. It is probably that Daur is not thedirect descendant of Khitan.In this paper, the ancient DNA sequences of Khitan population werestudied. The analysis of genetic structure, race, origin and descendent etc.developed the studies of Khitan on molecular genetics, and provided the cluesto the history, archeology and ethnology. By analyzing the origin anddescendant of Khitan, we obtained some molecular genetic evidences on thedisputed questions of the Khitan study. By discussing the nobles and race ofKhitan, the results of archeology and physical anthropology were validatedand complemented. Furthermore, by researching the genetic structure ofKhitan, we obtained more knowledge of Khitan population on moleculargenetics. |
PDF Full Text Request