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General Session 3: Biological oceanography & global change |
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Gene flow, genetic structure, and adaptability differentiation of stony coral Galaxea fascicularis around Hainan Island
Tuesday 10th @ 1605-1625
Multi-function Hall
Yan Wang* , State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Dingjia Su, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Jing Hou, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Ying Wu, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Li Cheng, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Xiaoqing Chen, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Tao Xu, State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, Hainan, 570228
Presenter Email: ywang@hainu.edu.cn; wy2005@163.com
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| Background: The coral reefs around Hainan Island are continuous fringing reef, located at the northern edge of continuous reef of the India Pacific. The coral reefs provide an important natural barrier for the protection of the sandy coast of Hainan Island. However, the coral reefs around Hainan Island have been declining continuingly in the past few decades in the context of global climate and environment changes. Galaxea fascicularis, a broadcast-spawning massive coral, is one of the most common and representative coral species in the fringing reef around Hainan Island. Research goals: In order to clarify the variation of genetic diversity of its metapopulation, and analyze the genetic connectivity resulting from larvae migration along with the ocean currents in an evolutionary time scale, (Methods) we developed the microsatellite markers to analyze the population genetic structure and gene flow of this species in Hainan fringing reef. Results and Discussion: The results showed that, the ratio of homogeneous fragments (6.7%) of the eastern and northern populations was higher than that of western (3.0%) and southern populations (2.2%), possibly due to the destruction of the typhoon and local fishery operation mode. And the ratio of microsatellite loci deviated from Hardy Weinberg equilibrium (HWE) of the eastern and northern populations were significantly lower than that of the western and southern populations, suggesting more significant random mating feature in eastern and northern populations. While in the west and the south, the substructuring of the population sample and inbreeding resulting from the higher density and structural complexity of the stony corals community, may lead the populations deviate from HWE. Compared with the G. fascicularis populations around Hainan Island, Yongxing population from Paracel Islands was the only one experienced population bottlenecks, showing the highest inbreeding coefficients (FIS, 0.44), followed by the western (mean FIS, 0.39), the southern (0.31), the eastern (0.27) and the northern populations (0.18) around Hainan Island. About genetic diversity, Yongxing population had the lowest number of allele and allele richness (4.6/4.3), and then is Basuo (6.9/5.3) and Luhuitou Populations (7.9/5.4). While population Fenjiezhou (13.9/7.6) and Mulantou (9.3/7.1) had the highest. Observed heterozygosities were ranged from 0.33 (Basuo) to 0.69 (Mulantou), in overall those of the northern and eastern populations were higher. As for genetic differentiation and the clustering among populations, the G. fascicularis population of Yongxing Island appeared significant genetic differentiation (with an average FST of 0.201), making itself a separate clade. For those Hainan populations, the four southern populations having the minimum differentiation (mean pairwise FST 0.041), were first clustered into the first branch; those three populations of the eastern and the northern clustered into the second branch (mean FST 0.080), and then the two branches merged with the third branch, which was clustered by two western populations (mean FST 0.100). The minimal genetic differentiation were detected between Mulantou and Leigongdao population (mean FST 0.040), as well as among the four southern populations, indicating in Qiongzhou Strait and the south of Hainan Island (between Luhuitou and Hongtang Bay) there might be the active coral larvae migration path, in an evolutionary time scale. Furthermore, we recently found that part of the G. fascicularis colonies with the microbasic p-mastigophores (MpM) of tentacular nematocysts type H (Mt-Long haplotype) had a special zooxanthellae symbiosis (zooxanthellae-specific microsatellites MSGf genotype G2). Compared with MpM S (Mt-Long haplotype) colonies (MSGf genotype G1, the two morphs were previously found part reproduction isolation), the concentration of zooxanthellae (MSGf-G2) in MpM-H coral increased faster in the first 3 h and then reduced slower during 32℃ heat treatment, which probably had a stronger heat-bleaching resistance. This finding might help to select high temperature-resistant G. fascicularis strain for human-assisted evolution so as to build the coral reef resilience. On the other hand, it raised an interesting hypothesis: the differentiation of the external morphology in coral might lead to the change of the symbiotic algae, which in turn changed the adaptability and finally resulting in speciation. Keywords: Gene flow; Genetic structure and connectivity; Larvae migration; Stony coral Galaxea fascicularis; Hainan Island |
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