Abstract
中文摘要台灣鉤吻鮭為瀕臨絕種的保育類動物，其遺傳多樣性是否趨向於均質化，是值得注意的問 題。本研究除了利用同功異構脢電泳法分析台灣鉤吻鮭的族群遺傳結構，另外，使用DNA 定序的方法分析台灣鉤吻鮭與日本櫻花鉤吻鮭族群內、族群間的遺傳多樣性。在同功異構脢電泳分析中，23個基因座只有一個有遺傳變異，平均觀測(Ho)與平均理論質 異度(He)為0與0.0115，表示其基因多樣性偏低。利用F-統計分析結果，族群之近交係數 (FIS)為一，顯示台灣鉤吻鮭頃向於近親交配，族群間變異指數(FST)為0.081，表示族群 幾乎沒有分化。在粒線體DNA序列分析方面︰(1)日本櫻花鉤吻鮭的洄游族群與陸封族群間的遺傳距離 (0.0045-0.0058)遠大於族群內的遺傳距離(0以及0.0039)，因此推測洄游型與陸封型之間 有逐漸分化的趨勢；(2)台灣鉤吻鮭與日本陸封型櫻花鉤吻鮭不論族群內或族群間的遺傳 距離非常小（0.001-0.0039），這應該是太平洋鮭屬中共同的現象，但日本族群內的歧異 度（七個個體分成四個基因型）仍大於台灣族群（十二個個體只分為兩個基因型）； (3)台灣族群內的遺傳多樣性貧乏，兩種基因型中只有一個鹼基對的變異，遺傳距離僅有 0.001，但遺傳多樣性尚未到達完全均質化的情況。因此要如何保存、增加台灣鉤吻鮭的 遺傳多樣性為保育台灣鉤吻鮭的重要工作。AbstractThe genetic diversity of the endangered species Oncorhychusmasou formosanus,has attracted increasing attention. This studyapplied isozyme electrophoresis and mitochondria DNA sequencingto analyze the genetic diversity within and among populationsin Taiwan and Japan.As the isozyme experiment results indicated, only one out oftwenty three loci expressed minor genetic variations. Itimplies low genetic diversity(Ho=0), and the F-statisticanalysis demonstrated the populations in Taiwan tended toinbreed.The DNA sequencing data lead to three main conclusions: One, thegenetic distances between anadramous and landlockedpopulations in Japan is far greaterthan the distances withinpopulation, which indicated that anadramous and landlockedpopulations are gradually diverging. Two, landlocked populationsin Taiwan and Japan differ genetically slightly. This situationis common among Pacific salmon genera. However, thediversity of the Japan population (four genotypes in sevenspecimen) is greater than that Taiwan's (two genotypesin twelve specimen). Three, the Taiwan population exhibits lowgenetic diversity. The base pair difference between the twogenotypes dedicates a genetic distance of 0.0001. As aresult, one of the essential efforts to preserve thisprecious species lies on maintaining and increasing thegenetic diversity of the population.