The Genetic Variation Of Achnatherum Splendens Populations And Ecological Adaptation To Soil Salinity

Molecular ecology and ecological adapation are research focus of ecology in recent years. Achnatherum splendens distributes in the arid and semiarid areas of Eurasia, and Achnatherum splendens community is main vegetation type in typical and desert steppes in Northern China. The technique of random amplified polymorphic DNA(RAPD), Nei's index and Shannon index are used to assess genetic diversity of 13 natural populations of Achnatherum splendens which distribute in Qinghai-Tibet and Inner Mongolian Plateau in this paper.The soil electric conducti-vity at 12 sites with the distribution of A. splendens and its adjacent zonal communi-ties in Inner Mongolia and Qinghai was determined, aimed to reveal the effects of soil salinity on the spatial distribution of A. splendens community at habitat and regional scales, and to analyze the vegetation property of A. splendens community based on soil salinity characteristics. The results as follows:1. A. splendens have high the genetic diversity and strong adaptation. The percentage of polymorphic loci is 93.69% among A. splendens. The total genetic diversity index of A. splenden separately are 0.2216 and 0.3523 using Nei's index and Shannon index.2. Nei's index shows genetic variation of A.splendens populations is low, and the more genetic and variation arise within population, and few arise among populations.Genetic variation reduce and genetic low increase with the scale shrinking.3. On a large scale of Qinghai and Inner Mongolia, the correlation of the genetic distance and geographic distance is significant to A. splendens. The genetic distance have correlation with geographic distance in Inner Mongolia, but have no correlation in Qinghai.4. The correlation of genetic diversity and Geographical coordinates and altitude is significant to A. splendens, but have no correlation with precipitation and temperature, have correlation with soil salinity.5. At regional scale, no direct correlation is observed between soil salinity and the distribution of A. splendens community. A. splendens can form community both on salt-rich and on salt-poor soils, being a saline-resistant plant with wide ecological amplitude. At habitat scale, A. splendens community is always found on the soil with higher salinity, compared with adjacent zonal Stipa community, implying that Stipa community is less saline-resistant.6. A. splendens have a wide distribution in high salinity soil environment in Qinghai, more higher djacent zonal Stipa community.7. The feature of soil salinity about A. splendens community imply its azonal vegetation characteristic. The distribution of A. splendens community has no direct correlation with precipitation.