尖枝列孔珊瑚

Seriatopora hystrix

  尖枝列孔珊瑚 (Seriatopora hystrix) 為孵育型 (brooding) 珊瑚，廣泛分布於印度、西太平洋珊瑚礁區，在台灣除了北海岸及澎湖群島外，皆有其分布。先前研究指出，在不同空間尺度下，尖枝列孔珊瑚族群的分布受距離隔離效應或生態選汰而產生遺傳分化，但目前在台灣海域的相關研究仍很少。本研究樣本採集自南沙太平島、墾丁核三廠出水口、跳石、佳樂水、蘭嶼、台東三仙台與宜蘭豆腐岬七個地點，共285個樣本，利用6組微衛星 (microsatellite) DNA基因座為分子標記，進行基因型 (genotype) 分析，探討尖枝列孔珊瑚不同空間尺度的族群遺傳多樣性 (genetic diversity) 及遺傳結構。結果顯示，無論在小尺度 (3 ~ 25 km) 或大尺度 (> 1700 km) 範圍之下，族群之間皆有顯著的遺傳分化 (genetic differentiation)，此遺傳分化程度與地理距離沒有顯著相關 (r2 = 0.030, p = 0.705)。另外，太平島族群遺傳多樣性較高，且含有二個獨特基因型。綜合上述結果，此種珊瑚的族群遺傳結構在不同空間尺度下呈現不一致變化，可能受到珊瑚的生活史特徵或環境選汰等多重因子交互作用影響，而導致沒有明顯的距離隔離效應。

  It has been hypothesized that the isolation-by-distance effect and ecological selection could lead to high level of population subdivision in different spatial scales. Here we investigated the genetic diversity and genetic structure of a common brooding coral Seriatopora hystrix in various geographic scales in Taiwan by using 6 microsatellite markers. Totally, 285 samples were collected from 7 sites including Taiping Island in the South China Sea, the outlet of the Third Nuclear Power Plant, Tiaoshi and Jialeshuei in Kenting National Park, Lanyu and Sanxiantai in Taitung County, and Tofujia in Yilan County. Our results showed that the population of Taiping Island had higher genetic diversity and two unique genetic clusters could be identified. Significant genetic differentiation was detected among all populations at both small (3~25 km) and large (> 1700 km) geographic scales, and this pattern was not associated with geographic distance (r2 = 0.030, p = 0.705). This study demonstrates that the isolation-by-distance effect may be modified by ecological selection or interactions between environmental factors and life history traits.