Genetic Structure And Connectivity Of Scleractinian Coral Galaxea Fascicularis Around Hainan Island

Considerating the rapid degradation of coral reefs,China's coral reefs have been reduced by at least 80% in the past 30 years. At present, the key to maintain the stability of coral reef ecosystem is to establish coral reefs Reserve to protect coral reef populations. In this study, we artificially bleach the scleractinian coral, Galaxea fascicularis,through elevating water temperature and obtain the released zooxanthellae to extract pure zooxanthellae DNA.And the genomic DNA of the partly bleached coral-algae symbiote is enrich for microsatellites.and the resulting primers are tested against pure zooxanthellae DNA templates.Using the G.fascicularis microsatellite markers and microsatellite loci we already developed, we will detect the population structures and genetic connectivities of galaxea fascicularis in xisha islands and among hainan island.1 .Microsatellite sequences were isolated from partly bleached coral-algae symbiote by using the magnetic bead hybridization enrichment method, 19 clones were discovered to contain microsatellites through sequencing analysis From 50 positive clones. 16 pairs of primers were designed from the microsatellite flanking sequences successfully.2.In this paper, a set of identification methods for the identification of coral and its symbiotic algae's microsatellite marker was established. Through the identification,we have developed 4 microsatellites markers of host coral, and 3 microsatellite markers of zooxanthellae. Combined with the microsatellite markers developed in this study, a total of 7 pairs of primers were selected for the experiment.3.The presence of 3.2% of individuals in 10 populations of Galaxea fascicularis came from other asexual breeding system , indicating that typhoon or human causes of coral regeneration ratio was not high.4.After Bonferroni correction, Two among Seven microsatellite loci deviated from Hardy-winberg equilibration in the Mulan group (2Gm) and the Changqi group(Cq). four in other groups and even up to seven loci deviated from Hardy-weinberg equilibration. The average number of value of the loci of deviating from HWE in the eastern and northern groups of Hainan is less than the average number of deviating loci of the southern population and the average number of deviating loci in the western population. These findings directly suggest that the coral may not be a complete random free mating, the shape of the coral itself and the different geographical location in which the complex marine geography of the formation of the ocean circulation and eddy currents caused.5.The lowest inbreeding coefficient was 0.13 in the population of Mulantou(2Gm), the other 9 populations were greater than 0.25, the largest population(Gb) was 0.44,It shows the intermittent characteristics of asexual reproduction and sexual reproduction of coral.Migration of sexual reproduction may be limited on a geographic scale.6.The average number of alleles are 4.6-9.9,the average allele abundance is 3.7-6.7, the average expected heterozygosity is 0.61-0.83, the average observed heterozygosity is 0.33-0.69, showed The genetic diversity of 10 different geographical populations is medium. Among them, the genetic diversity of the population of XiSha(Gx) and Basuo (Gb) is the lowest, and the genetic diversity of the population is the highest.7.The consistent results of cluster analyses using Nei's Da Distance methods and STRUCTURE were detected, it was showed that 10 populations were divided into four groups, and the first group contained Basuo population and Leigongdao population. The second group containd Hongtanwan population(Gr),Xidao population(Gw), Luhuitou population (2Ge) and Houhai population(Gs) ,they are located in the south of the Hainan Island.The third group contained three populations distributed from east to north of the hainan island. The last group contained Xisha Islands. The ocean currents are the main approach for gene flow.8.From the genetic differentiation among populations, Galaxea Fascicularis,its population in XiSha Islands have significant genetic differences with the populations around Hainan Island. Between the Basuo population(Gb), Hongtanwan population(Gr) and Leigongdao population(Gg) respectively,between Mulantou population(2Gm), Leigongdao population(Gg),and the Changqi population(Cq)respectively; between Fenjiezhoudao population(Gf) ,the Changqi population(Cq) and among population in the southern of the hainan island,have smaller genetic differentiation, revealing the geographical location between these populations is the site as coral Larvae migrate to actively.9.The gene flow of the southern populations (Gw, 2Ge, Gs), the southeastern population (Gf) in Hainan Island and the Xisha population (Gx) showed that the gene exchange value was greater than 1. While these populations around Hainan Island,geographical distance close to the groups,have a larger gene flow. From the molecular biology point of view indirectly verify the transport path of coral larvae from Xisha Islands to the south of the hainan island,Then through the eastern part of the final arrival of the northern part of Hainan Island.