Analysis Of Community Ecology And Genetic Diversity In The Relic And Rare Plant Euptelea Pleiospermum Hook. F. Et Thoms.

Euptelea pleiospermum Hook.f.et Thoms.a deciduous shrub or small tree,belongs to Euptelea Sieb.& Zucc.Of the monotype family Eupteletaceac in E Asia.The family consists of only Euptelea,with two species,i.e.,E.pleiospermum in India,Burma and China as well as E.polyandra Sieb.& Zucc.in Japan and Korea E.pleiospermum is not only named as the national third class conservation plant species as well as the typical East Asia floristic element,but also an archaic relict plant species.Studies on this species can enrich the knowledge about its floristic composition and plant phylogeny.Present studies on E.pleiospermum mainly focus on its morphology,anatomy and cytology, there are few comprehensive studies,particularly lack of the relatively quantitative analysis.The distribution range and population numbers of this species became very restricted,which indicates the danger of extinction if further fragmentation of the habitats occurred.It is necessary to study the endangering mechanism and then do reasonable protection of this species.The present paper mainly focus on the studies on community ecology and genetic diversity of this rare and relic species.The results are as follows:1)Through general community ecology investigation and Two-way indicator Species Analysis (TWINSPAN),the 32 plots where E.pleiospermum populated are classified into 7 associations,i.e., Eupetlea pleiospermum-Symplocos caudate -Iris tectorum association;Eupetlea pleiospermum + Cunninghamia lanceolata-Berberis soulieana-Cardiocrinum giganteum association;Eupetlea pleiospermum - Cornus officinalis + Prunus dielsiana-cyrtomium fortunei + Corydalis edulis association;Eupetlea pleiospermum + Cornus controversa - Viburnum brachybotryum-Viola philippica + Duchesnea indica association;Eupetlea pleiospermum +Hydrangea strigosa-Ophiopogon bodinieri association;Eupetlea pleiospermu-Broussonetia papyrifera-Pileacadierei association;Lindera megaphylla-Eupetlea pleiospermum - Iris japonica + cyrtomium fortunei association. 2)DCA 2D ordination more visually shows the influence of the environmental factors on the community structure.The ordination results both of 32 plots and 91 species show the same trend. About 1200 m above sea level is the area where,E.pleiospermum mostly distributed.With the elevation fall,less individuals can be found.Individuals in habitats lower than 800 m will rarely be collected.Due to the influences of the environmental factors and the artifical disturbance, individuals of E.pleiospermum became less and more scattered along with the right axis 1 in the ordination plot.Habitat destruction results in the death rates of individuals became higher.3)Establish the RAPD analysis system is established for E.pleiospermum.The optimum concentrations of five important components are Mg²⁺1.5mmol/L,dNTP 0.16mmol/L,DNA 50ng, Taq DNA 1.25U,Primer 0.24μmol/L.Modified thermal profile consisted of an initial denaturation step at 94℃for 4min;follow by 35 cycles of 94℃for 60s,36℃for 30s,72℃for 80s;and a final exposure to 72℃for 10min.Then stored in 4℃.4)The amplified results show that the E.pleiospermum's total proportion of polymorphic sites is 87.18%.Genetic diversity within populations is 2.9779 estimated by Shannon index,and average intraspecific genetic diversity is 3.6584.Making an estimate through Shannon index,10 primers detect in the five populations' genetic differentiation is 18.41%.According to Nei's genetic differentiation index estimated the total population genetic diversity is 0.3162,and the genetic diversity within groups is 0.2648,among groups the genetic diversity is 0.0514.Gene differentiation coefficient is 0.159.Results from two indices show that among populations molecular variation is the small part of the genetic diversity,most of the genetic variation exist within populations.5)The matrix for five populations display that:Genetic distanc between pop1 and pop2 just 0.0294,the highest Genetic Identity is 0.9215 between pop4 and pop5.The dendrogram based on Nei's genetic distances clustered by UPGMA show the same result:Genetic distances among populations and their actual geographical distances are basically correlated.6)Based on the stidies on the community ecology of E.pleiospermum,it suggested that insitus protection with strictly cutting activities control should be applied in area with high human interfrences.And in intensive distributed area,natural reservation districts are suggested to be build up in purpose of preventing the species from destructive using and human interference,as well as activating the ecological and economical benefits of Eupetlea pleiospermum.Moreover,it is highly recommend to introduce the species in botanic gardens for ornamentation and even for urban afforestation.