Adaptive Divergence of Genetic and Epigenetic Variations in Taiwania cryptomerioides Hayata

• Main Authors: Li, Yi-Shao, 李翊韶
• Other Authors: Hwang, Shih-Ying
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/83rbym

碩士 === 國立臺灣師範大學 === 生命科學系 === 106 === The interactions of neutral drift and naturel selection have received much attention from population geneticists because they may increase the level of differentiation between populations and potentially facilitate biological speciation. Taiwania cryptomerioides Hayata whose populations are now only distributed within mountainous cloud forest regions of northern Vietnam, Yunnan-Myanmar border of China, and Taiwan Island, ranging from 1600 – 2500 m a.s.l. We surveyed genetic and epigenetic variations of eight extant populations of Taiwania through two dominant markers, AFLP and MSAP, and then we finally obtained 1413 AFLP loci and 462 MSAP loci. The results suggested that large proportions of polymorphism loci and relatively high levels of genetic and epigenetic diversity in populations of Taiwanese lineages of Taiwania than those of Chinese and Vietnamese lineages. We also found there were significant levels of genetic and epigenetic differentiation between Taiwanese and mainland Asia lineages revealed by pairwise FST and STRUCTURE. Neighbor-Net phylogenetic network demonstrated the close relationship between Yunnan-Myanmar and Vietnamese lineages differentiated from Taiwanese populations, both results suggested Taiwania populations can be devided into two distinctly distinguishing clusters when K=2. In DFDIST and BAYESCAN analyses, no potential selective outliers were found within Taiwanese populations due to strongly neutral drift induced divergence. 32 loci were identified as potentially selective ouliers associated strongly with environmental variables including seasonary temperature (BIO4), seasonary precipitation (BIO15), and NDVI in either global or pairwise lineage comparisons. Not only had these important environmental variables influenced genetic and epigenetic variations, but they also had driven adaptive divergence and population differentiation of Taiwania with random drift. Therefore, the standing genetic and epigenetic variations either determined by selection or fixed by neutral drift, they both may ensure the capacity of Taiwania for adaptations to rapidly varing environment or climate change, and ability to survive and reproduce in the future.