Genotypic Diversity And Its Relationship To Invasive Ability Of Spartina Alterniflora

Recently, people found that plant genotypic diversity could pedict community structure and govern processes of an ecosystem. It may functionally replace of the roles of species diversity in species-poor ecosystems, such as seagrass. The invasive plant Spartina altermflora is one of dominant species in Dongtan of Chongming, so the its genotypic diversity may have community-or ecosystem-level consequences.We investigated the genetic diversity of the populations of Spartina altermflora, and studied the invasive ability of different genotypic diversity, then revealed the relationship between the genotypic diversity and ecosystem function by SSR and a field experiment.Sixteen populations and 477 individuals were sampled and genotyped to reveal the genetic structure. We detected a total of 38 different SSR alleles by 6 primers. At population level, mean number of alleles per loci was 6.333, Shannon diversity index was 0.703, the genetic diversity within populations (Hs) was 0.420, genetic diversity among populations (D_ST) was 0.200, and total genetic diversity (H_T) 0.620. Most of genetic diversity was within populations. But there is also the differentiation among populations. Nei's gene diversity coefficient (Gst) was 0.322, with gene flow (Nm) of 0.491, indicating geographical isolation between the populations.Genetic diversity indexes between populations were different largely. South Carolina of USA (FB) and Chongming of Shanghai (CM) had the highest diversity, followed by Luoyuan of Fujian Province (LY), Yancheng (SY), and Qidong (QD) of Jiangsu Province. Jinshan of Shanghai (JS), Haicang of Xiamen (HC), Weifang(WF), and Rizhao of Shandong Province (RZ) had the lowest diversity. The results were coincided with the introduction route in which Luoyuan of Fujian Province and Jiangsu Province were locations that S. alterniflora was first introduced. The genetic distance of populations ranged from 0.031 to 1.462, and the average was 0.478. The genetic identity was from 0.232 to 0.969, and the average was 0.653. We concluded the populations of Weifang (WF) and Rizhao (RZ) were Spartina anglica.We studied the 22 clusters of Spartina alterniflora in Chongmin and found there were different clones among clusters, but same within cluster. Using a field experiment, we tested the relationship between the genotypic diversity and plant invasive ability. We found high number of seed output of genotype D, but its single seed weight is much lower than other genotypes. There was a trend that genotypic diversity increased the invasive ability including of the number of root,dispersal area and single seed weight. "Overyielding" occurred in three-genotype treatment. But there were no statistical differences among different treatments. Thus, above results suggested genotypic diversity might enhance the invasive ability of Spartina alternijlora.