Broussonetia papyrifera Vent. of Moracea, is a native riparian and dominant tree species at the altitude from 0 to 2000m in Taiwan. Since gene flow is suspected to be restricted mainly within a single river system, we hypothesize that plants of each river system might have rather distinct genetic structure due to limited gene flow. In the present study, 180 individual samples from 18 sampling sites (populations) in five river systems were studied using ISSR markers. The variation of 93 polymorphic ISSR bands, 78 bands were polymorphic in the samples were recorded. Analysis of the population genetic variances demonstrated that there were unremarkable Nei's genetic diversity, and conspicuous population differentiation between different river systems (H=0.1624, Gst=0.2476), with high level of gene flow (Nm=1.5192). The results were probably due to that the influence from the different environments did not restrict the gene flow but promote a lower genetic differentiation. The analysis of molecular variance (AMOVA) revealed that the components of variance among river systems was 24.21% (p<0.001). Among populations within river systems was 13.01% (p<0.001). Main variance within populations, shown to be significant, was 62.78% (p<0.001). The results indicated that there is a considerable genetic diversification among river systems, and most of the diversification was between populations. Based on our mantel test, correlation coefficients among genetic variation among for 18 natural populations were significant, influenced by the geographical distribution but uninfluenced by the elevation. The cluster analysis and principal coordinate analysis revealed two major general groupings of northern and central-southern groups. The Gao-ping-shi river system was found to be a relatively isolated group by the cluster analysis. Cluster analysis and principal coordinate analysis (PCOA) also revealed that the genetic differentiation may be caused by different environments.
Broussonetia papyrifera Vent. of Moracea, is a native riparian and dominant tree species at the altitude from 0 to 2000m in Taiwan. Since gene flow is suspected to be restricted mainly within a single river system, we hypothesize that plants of each river system might have rather distinct genetic structure due to limited gene flow. In the present study, 180 individual samples from 18 sampling sites (populations) in five river systems were studied using ISSR markers. The variation of 93 polymorphic ISSR bands, 78 bands were polymorphic in the samples were recorded. Analysis of the population genetic variances demonstrated that there were unremarkable Nei's genetic diversity, and conspicuous population differentiation between different river systems (H=0.1624, Gst=0.2476), with high level of gene flow (Nm=1.5192). The results were probably due to that the influence from the different environments did not restrict the gene flow but promote a lower genetic differentiation. The analysis of molecular variance (AMOVA) revealed that the components of variance among river systems was 24.21% (p<0.001). Among populations within river systems was 13.01% (p<0.001). Main variance within populations, shown to be significant, was 62.78% (p<0.001). The results indicated that there is a considerable genetic diversification among river systems, and most of the diversification was between populations. Based on our mantel test, correlation coefficients among genetic variation among for 18 natural populations were significant, influenced by the geographical distribution but uninfluenced by the elevation. The cluster analysis and principal coordinate analysis revealed two major general groupings of northern and central-southern groups. The Gao-ping-shi river system was found to be a relatively isolated group by the cluster analysis. Cluster analysis and principal coordinate analysis (PCOA) also revealed that the genetic differentiation may be caused by different environments.