摘要
親緣地理學探討物種演化及播遷的時空分佈。台灣島與中國東南沿岸中間阻隔的台灣海峽在過去的冰河時期海平面降低，形成陸橋，兩邊生物的起源及分佈的歷史與路徑是研究親緣地理學的適當題材。台鰍屬Formosania魚類是純淡水性的底棲性魚類，分布在台灣以及中國大陸東南沿海河川。由於生活在河川中上游急流中、需氧量高又無法短暫存留於海水中，是不會受到人類活動干擾的非經濟性魚種，因此適合以此類群的魚類做親緣地理學研究。本研究採用台鰍屬魚類Cyt b基因作為分子標記，對台鰍屬魚類做系統發育研究，並依據得到的親緣關係，以及古地理事件，推測台鰍屬魚類分支演化及擴散的時空變化。 台鰍屬包含8個種，本研究期間採樣地包括台灣以及中國東南浙江福建廣東沿岸的溪流。測量外部形質並定序Cyt b基因，以Neighbor-joining (NJ)分析法建構親緣關係樹，Nested Clade Analysis分析群聚關係。依親緣關係發現台灣台鰍F. lacustre不只分佈在台灣，還分佈在福建晉江、木蘭溪以及桐山溪。而斑紋台鰍分佈在交溪、閩江以及韓江。花尾台鰍F. fascicauda侷限分佈在九龍江。陳氏台鰍(F. chenyiyui)分佈在韓江。分子生物學的分析方法釐清了過去班紋台鰍F. stigmata、花尾台鰍共域的文獻記載，並且發現了台灣台鰍在中國沿岸溪流的分佈。依據NCA分析提供台鰍類群族群擴張的相互連結關係，並且配合古地理事件，推測台鰍類群的共同祖先應該是由武夷山以北的長江地區起源，往南遷徙，約900萬年前到福建沿海一帶形成台鰍的祖先，其後約400萬年前在閩江一帶形成斑紋台鰍的祖先、在晉江一帶形成台灣台鰍的祖先。約250萬年前，九龍江族群與以北的族群分隔，形成現今的花尾台鰍。約150萬年前台灣台鰍因冰河時期海平面下降而播遷到台灣，而其後的冰河期也使得以播遷來台的台灣台鰍因兩岸水系有機會連結，而回到木蘭溪。斑紋台鰍在120-140萬年前，因為東閩江的向源侵蝕，侵蝕了閩中大山，襲奪西閩江，使得原本分布在東閩江的斑紋台鰍藉由西閩江進入汀江及韓江，交溪的斑紋台鰍則推測是因為冰河時期海平面下降而擴散所致。
並列摘要
The genus Formosania is distributed in mountain streams in Taiwan and in south-eastern coast rivers of China. Their limited dispersal ability, the needs of high contents of dissolved oxygen in freshwater, and being considered economic invaluable make them appropriate materials for study of the biogeography across Taiwan Strait. We collected Formosania spp. samples from central-western to north-eastern Taiwan, and south-eastern rivers (from Pearl R. to Fei-Yun R.) in China. F. stigmata is the most widely distributed species in geography, it is found in Jiao-Xi R., Min-Jiang R., and Han-Jiang R.; F. lacustre is not only found in Taiwan, but also in Mu-Lan R., Jing-Jiang R. in China; F. fascicauda is found only in Jiou-Long R., which is different from previous records. We sequenced Cyt b gene, followed by Neighbor Joining tree analysis, and Nested Clade Analysis. We found that F. lacustre was closely related to F. fascicauda, and then F. stigmata. F. chenyiyui, however, was closely related to Vanmanenia, the genus most related to Formosania. By molecular dating and geographical events referring, we speculated the time and migration pattern of the genus Formosania: the ancestors of Formosania might originate in Yangtze R., nearly 9 million years ago they migrated to the south-eastern coast area of China; around 4 million years ago, in eastern Min-Jinag R. drainage, the ancestors of F. stigmata formed. Meanwhile, in Jin-Jiang R. and Jiou-Long R., the ancestors of F. lacustre and F. fascicauda formed. About 1.5 million years ago, the population in Jiou-Long R. separated from that of Jin-Jiang R., F. fascicauda appeared. Between 1.4-1.2 million years ago, the headwater stream of eastern Min-Jiang R. captured the western Min R., the F. stigmata in eastern Min R. followed the connected river systems to Han-Jiang R.. In latest glacial age, F. stigmata migrated from Min-Jiang R. to Jiao-Xi R.. The Formosania sp. population in Mu-Lan R. was previously classified as F. fascicauda or F. stigmata, but the Cyt b gene analysis and morphological comparison indicated a strong similarity of this population to F. lacustre. We speculate that the population in Mu-Lan R. was formed in the latest ice age when F. lacustre dispersed from Taiwan to Fujian coastal region, remained in Fujian during the interglacial period.
參考文獻
Mori, T. (1936) Studies on the geographical distribution of freshwater fishes in eastern Asia.
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