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Evolutionary Genetics Of Pinus Henryi And Its Relative Species Using CpSSR And AFLP Markers

Posted on:2008-02-15Degree:MasterType:Thesis
Country:ChinaCandidate:X YangFull Text:PDF
GTID:2120360215964614Subject:Botany
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Pinus henryi Mast., an endemic species in QinBa mountains of China, mainly distributes over Daba mountains, Wushan mountains and offshoots of YunGui plateau. Most forest of Pinus henryi have been destroyed by man and this species is listed as rare plant.Pinus henryi is often regarded as taxonomic variant species of P. tabuliformis or P. massoniana. Several experts argued that it should be independent species based on the differences of timber anatomy and chemical components. According to geographic distribution, P. henryi is linked together with P. tabuliformis in north, neighbor with P. taiwanensis in east, crisscross with P. yunnanensis in south, and overlap with P. massoniana (lower at altitude). Complicated relationships exist in Pinus henryi and its relative species due to similar morphic characteristics, overlapped distribution and extended hybridization in pines. Making use of amplified fragment length polymorphism (AFLP) and chloroplast simple-sequence repeat (cpSSR) markers, we analyzed molecular Phylogenetics, gene diversity and genetic differentiation in these five Eurasian pines. The study would identify phylogenetic relationship of P. henryi and its relative species, and imply for protecting and utilizing the special pine resources in China.The results were as follows: Firstly, high genetic differentiation and median gene diversity with cpSSRs markers were found both at population and species level while median differentiation and higher gene diversity with AFLPs data. Although the Infinite Allele Model were preferred at most chloroplast gene loci, other models should not be rejected according to the similar support rates. Measures of subdivision that consider similarity between haplotypes offered better information of plant geographic structure than the standard ones. Among several methods analyzed in AFLPs, Sequare root method provided downwardly biased estimates of the genetic parameters, while Lynch and Milligen method over-estimated genetic diversity due to limited samples. Thus Bayesian statistics was the most accurate and popular method in those data with the dominant markers and its value of species differentiation (θ~B = 0.1035 ) was close to the parameter given by Analysis of Molecular Variance (AMOVA).Secondly, it was evident that P. henryi was an independent species and close to P. taiwanensis using both cpSSRs and AFLPs data with high bootstrapping supports. P. henryi and its relatives shared more common genetic components given by AFLPs than those offered by cpSSRs results, which suggested that late divergent time or frequent gene flow might contribute to phenomena of the shared genomes.In addition, taking P. henryi and its relative species for example, sampling strategy and statistical methods were analyzed by chloroplast microsatellites (cpSSR) and AFLP markers. The results showed some differences with present views. It was phylogenetic relationships rather than genetic diversity that was notablely affected by sample sizes/loci and methods of phylogenetic trees construction.
Keywords/Search Tags:Pinus henryi, Genetic diversity, Genetic differentiation, Phylogenetic relationship, Sampling strategy, cpSSR, AFLP
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