墾丁國家公園的籬枝同孔珊瑚宿主遺傳結構與共生藻群聚之時空變異

Spatial and temporal variations of host genetic structure and symbiont community in the catch bowl coral, Isopora palifera (Scleractinia; Acroporidae), in the Kenting National Park, Taiwan

方慧玲(Wai-Ling Fong)

指導教授 ： 陳昭倫

共同指導教授 ： 單偉彌(Vianney Denis)

國立臺灣大學/理學院/海洋研究所/碩士(2016年)

https://doi.org/10.6342/NTU201603599

摘要

全球的珊瑚礁正受到人為干擾跟海水溫度上升的威脅，要保護日漸消失的珊瑚礁，需要有系統的管理策略跟豐富的珊瑚對抗熱逆境生理機制的知識。本論文探討了墾丁國家公園的籬枝同孔珊瑚宿主的遺傳結構和共生藻親緣型群聚在空間上和時間上的變動差異。在2015年，我們在墾丁國家公園裡十一個採樣點共採集了368群體，利用六組新發展出來的微衛星序列作為分子標記，來分析籬枝同孔珊瑚的族群遺傳結構。另外，我們利用限制性片段長度多態性跟變性梯度膠體電泳分析以及定序方法去鑑定珊瑚體內共生藻群聚時空變異。實驗結果顯示籬枝同孔珊瑚族群的遺傳變異偏低，十一個族群之間交流偏少，族群間呈現顯著的分化，可分為兩個群集。而珊瑚體內的共生藻屬於C3 跟D1-1a親緣型，其空間分佈跟海水溫度有顯著關係，生活在核三廠出水口附近的籬枝同孔珊瑚群體大多與耐溫型D1-1a 親緣型共生藻共生，越遠離出水口，越多籬枝同孔珊瑚群體與熱敏感型C3親緣型共生藻共生。比較2000、2006、2009和2015年潭子灣籬枝同孔珊瑚的樣本顯示族群遺傳結構沒有時間上的改變，但珊瑚體內的共生藻親緣型卻隨時間波動。綜合宿主族群遺傳與共生藻群聚時空變化的研究顯示，南台灣墾丁海域籬枝同孔珊瑚對核三廠出水口所產生的熱逆境並沒有發展出宿主的遺傳適應，但是藉由共生藻洗牌效應是籬枝同孔珊瑚調適熱逆境的主要機制。

關鍵字

籬枝同孔珊瑚 ； 共生藻 ； 熱逆境 ； 微衛星 ； 族群分化 ； 熱馴化

並列摘要

Global coral reefs are suffering from anthropogenic impacts and warming seawater temperature caused by climate change. Proper management strategies and rich knowledge of their thermal tolerance mechanisms are essential in order to protect the declining coral reefs. In this research, spatial and temporal variations of coral host population genetic structure and the associated Symbiodinium community structure of Isopora palifera in Kenting National Park, southern Taiwan, were studied. In 2015, a total of 368 colonies of I. palifera were collected from 11 sites covering the entire coastal reefs in Kenting National Park. Six novel microsatellite markers were used to reveal the population genetic structure of coral host. Restriction fragment length polymorphisms (RFLPs), denaturing gradient gel electrophoresis (DGGE), and DNA sequencing of ribosomal gene regions were used to identify the spatial and temporal variations of Symbiodinium types. In host samples, low genetic diversity and connectivity of I. palifera populations were found. Population subdivision was observed in 11 populations, which were subdivided into two discrete clusters. Symbiodinium hosted by I. palifera predominantly belonged to ITS2 rDNA type C3 and D1-1a, its spatial pattern was significantly correlated to seawater temperature, with the thermal-tolerant type D1-1a Symbiodinium dominated in I. palifera colonies located at the reef adjacent to the Outlet of 3rd Nuclear Power Plant and thermal-sensitive Symbiodinium C3 gradually increased in locations away from the Outlet. Comparing the samples at Tantzei Bay (TZB) collected in 2000, 2006, 2009 and 2015, the host genetic structure remained the same, while Symbiodinium community structure fluctuated through time. Combining the results of the spatial and temporal variations of both coral host genetic structure and Symbiodinium community structure, it is showed that facing the heat stress caused by thermal effluent from the 3rd Nuclear Power Plant, Isopora palifera host did not develop genetic adaptation, while symbiont shuffling was the major mechanism for Isopora palifera in Kenting National Park to survive this thermal stress.

並列關鍵字

Isopora palifera ； Symbiodinium ； thermal stress ； microsatellites ； population subdivision ； acclimatization

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