Genetic Variation In Natural Populations Of Picea Asperata Mast.

Southwestern region plays an important role in economic development and ecological construction in China. Yet, it is also one of the weak regions of ecological environment in China with degraded ecosystem and imperfect function, which restricts the sustaining management and development of southwestern forestry. The genetic variation and spatial distribution pattern of P. asperata populations originating from different habitats were investigated using SSR molecular markers in this study. The correlations between genetic variation and ecological and environmental conditions were detected, and the interaction between P. asperata populations and environmental system and the mechanism of ecological adaption -molecular evolution were revealed. Given the significant ecological and economic roles of the fast-growing and wide-adaptive species inreforestation and production of pulp wood and timber, the study could provide a strong theoretical evidence and scientific direction for the sustaining management of subalpine natural forest, and the afforestation and rehabilitation of degraded ecosystem. The results are as follows:1. The genetic variation at SSR loci was abundant and the distribution of allelic frequencies was uneven. All seven loci were polymorphic, and the number of alleles per locus varied from 13 to 24 with a mean value equaling 19.9. The allele sizes at SSR loci were found to vary widely. 73.1% of allelic variation followed stepwise mutation model (SSM) which results increase or decrease by one repeat type, and 22.3% and 4.6% were resulted from two-phase mutation model (TMP) with allele size varying by more than one repeat type and from insertion-deletion events in the flanking regions at SSR loci with a single basepair changing, respectively.