Phylogeographic Structure Of Taxus Cuspidata Sieb.et Zucc

Taxus cuspidata Sieb.et Zucc,a tree species with high economic value and medicinal value because of its properties,subjected to serious man-made damage,is experiencing severe reduction in natural populations.Therefore,understanding the genetic diversity and structure of natural populations of the species has important value in evaluation and conservation of its genetic resources.T.cuspidata,is a Tertiary relic species,the molecular phylogeographic studies would provide strong evidences for understanding the genetic diversity and evolutionary history of T.cuspidata.In this thesis,three parental inherited chloroplast DNA(cpDNA)fragments and one maternal inherited mitochondrial DNA(mtDNA)were used to study the molecular phylogeographic,genetic diversity and genetic structure of the species.A total of 231 individuals from 25 populations of T.cuspidata across its distribution range in China were sampled to investigate the distribution of genetic diversity,genetic structure,and phylogeographic history for inferring the population dynamic history,which would provide basis for protection of this species.A high genetic diversity was revealed based on combined cpDNA region analysis:14 cpDNA hapolotypes and two mtDNA haplotypes were detected.The total cpDNA hapolotype polymorphism(Hd)is 0.86 and total nucleotide polymorphisms(?)is 2.5 × 10-4.The results of cpDNA data show that the genetic variation is mainly distributed within populations(98.5%)while the genetic diversity is very low among populations.Our cpDNA haplotype revealed that GST(0.10)is a little greater than NST(0.09),indicating no phylogeographic structure in T.cuspidata.For mtDNA,the total mtDNA haplotype polymorphism(Hd)is 0.44,and the total single nucleotide polymorphisms(?)is 4.0 × 10-4.Result of Fu's Fs show that populations of T.cuspidata in China may have experienced expansions.Our study suggests that the potential refugee of natural populations of T.cuspidate may distribute in the Changbai Mountains during the Quaternary glaciation,and we further Quaternary infer the migration routes of the species after the glaciation.Our results may provide a theoretical basis for cultivation,breeding and the resource protection of this important tree.