| Leymus chinensis was the main constructive species or dominant species in our country northern grasslands.However,due to the impact of human activities,the ecological environment has been greatly damaged and the natural vegetation is divided into different patch communities,which resulted in the significant decrease in species diversity.In this research,we study the 13 Leymus chinensis clonal patches of genetic diversity and genotype diversity by using ISSR molecular marker technology,which are different size and in the water restoration succession process,to reveal variation regularity of genetic structure and gene flow of L.chinensis clonal patches in the process of restoring succession,to protect grassland genetic diversity and provide the scientific basis for restoring degraded grassland and repairing the broken ecological environment.The results show that:(1)In the restoration succession process,the L.chinensis grassland produced rich genetic variation.Most of the genetic diversity index of the patch 8 and 6,which are the two largest patches,are bigger than other L.chinensis clonal patches.Meanwhile,the most of the genetic diversity of the patch 13 and 14,the smallest of the two patches,are smallest than others.It shows that the genetic diversity of L.chinensis clonal patch becomes larger with the increasing of patch area.In a patch,the center,transition,edge of three parts,their genetic diversity didn't show obvious regularity with the patch area.However,between the patches,center transition part of big patches showed more abundant genetic diversity than small patches,edge part of the patch didn't show obvious regularity.(2)There is a certain degree of genetic differentiation between 13 Leymus chinensis clonal patches and the gene flow between them is less than 1.But inside the patch,the gene flow is greater than 1 between the three parts of the center,transition,edge.It indicated that genetic differentiation between patches is mainly caused by genetic drift,while within the patch there is a strong gene flow,but it has nothing to do with the patch size.(3)Between the 13 Leymus chinensis clonal patches,center,transition edge portion of the genetic identy,genetic distance has nothing to do with the size of patch,but the genetic identy of the edge portion of the average minimum.In the same patch,there is no obvious regularity between the three parts of the genetic identity and genetic distance and patch area,but between the patches,the average of these parts of the genetic identity with the increase of patch area,it tends to dcrease.It shows that in the process of restoration succession,Leymus chinensis clonal patch portion of the genetic diversity more abundant.With the patch gradually propagate,the genetic identity of the patch inside decreases,genetic distance tends to increase.(4)Amaong the patches,the genetic variation comes mainly from populations.For a single patch,it's mainly due to patch inside.These show that L.Chinensis pollen dispersal distance is very limited.(5)Leymus chinensis clonal patch started by one or more genotypes of L.Chinensis individual amplified and reproduction.In the subsequent restoration succession process,except the eve,index gen,eff,div,shw,she,diu of genotypes diversity will increase with increasing of Leymus chinensis patch area.In addition,the edge portion of Leymus chinensis of Leymus chinensis genotype diversity is usually lower than the center and transitional part of Leymus chinensis genotype diversity. |
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