Genetic Differentiation Of Stipa (Sect. Leiostipa) Population Along The Meridional Direction In North Mongolian Plateau

The genetic differentiation of ecological adaptation is research focus of ecology, also is important content of landscape genetics in recent years.Stipa spp. are dominant plants in Europe-Asia steppes. In North Mongolian Plateau, five plants of Sect. Leiostipa Dum. which have similar characteristics with each other- Stipa baicalensis, Stipa grandis, Stipa krylovii, Stipa sareptana and Stipa capillata are roughly form a complete grassland vegetation zone, which has geographical and habitat alternative spatial distribution pattern. In this research, ISSR molecular markers technology was used to analysis the genetic diversity of population, relationship among populations, differentiation characteristics of intraspecific and interspecific, correlation of genetic diversity and geographic distance, correlation of genetic diversity and environmental factors. This study contribute to further reveal the spatial distribution pattern of genetic diversity, which comprehend differentiation mechanism and ecological adaptation mechanisms of Stipa spp. in Europe-Asia steppes, and also provide application value for biodiversity protection and sustainable utilization of grassland. The main results are outlined below.1. Each plant of Sect. Leiostipa Dum. has high genetic diversity, Nei’s index of each large population is:0.2204 (Stipa krylovii),0.2111 (Stipa baicalensis),0.1825 (Stipa grandis),0.2430 (Stipa capillata)、0.1548 (Stipa sareptana), except Stipa sareptana populations, Nei’s index of other large population were higher than the averages of monocotyledon (0.1900).Higher genetic diversity as genetic basis of each Stipa leads to more widespread.2. Except Stipa sareptana populations, genetic variation of other four Stipa populations show more genetic and variation arise among populations, and few arise within population. Among them, genetic variation among Stipa krylovii populations is 0.6430, within populations is 0.3570, genetic variation among Stipa baicalensis populations is 0.5563, within populations is 0.4437, genetic variation among Stipa grandis populations is 0.5397, within populations is 0.4603, genetic variation among Stipa capillata populations is 0.5438, within populations is 0.4562, and all value of their Nm<1, indicate there is a certain degree of genetic differentiation among populations which have weak gene flow. Two Stipa sareptana populations which have smaller geographical distance show more genetic and variation arise within populations, and few arise among population:genetic variation among populations is 0.3791, within populations is 0.6209, (0.3791<0.6209), value of its Nm>1.3. Five plants of Sect. Leiostipa Dum. which has similar characteristics and close genetic relationship with each other. In adjacent areas and in the same habitats of the Stipa population have genetic exchanging, also with relative independence. ISSR results showed less peculiar bands among Stipa populations (2 bands), population which from different Stipa populations clustering priority when based on genetic identity indicated by Nei’s index among 23 populations. Especially, the relationship between Stipa. grandis and Stipa. baicalensis,Stipa. krylovii and Stipa.capillata, Stipa. krylovii and Stipa. sareptana.4. Genetic distances among Stipa populations increases with the increase of geographical distance, correlation between the index of genetic and environmental factors (longitude, altitude,average annual temperature and total annual precipitation) is not significant.5. Geographical distances between groups is one of the important factors causing genetic differentiation, but local heterogeneity of habitat may also lead to a variety of genetic differentiation of Stipa spp. As a result, five plants of Sect. Leiostipa Dum. have spatial differentiation on large scale and habitat alternative spatial distribution pattern on small scale.