- 學位論文
台灣與日本地區日本鰻族群遺傳結構之時空分析
Spatial and temporal analysis of population genetic structure of the Japanese eel in Taiwan and Japan
摘要
本研究以微衛星 DNA 及耳石日周輪，分析 2001 至 2002 年所採集之各月份台灣與日本地區之日本鰻鰻線，並利用 2007 至 2008 年自台灣地區所採集之日本鰻鰻線進行成長率試驗，期望藉由這些試驗能夠進一步證實日本鰻南北分群的現象與機制。結果發現總遺傳分化指數極低且無顯著差異 (FST = 0.0002, p = 0.60)，在 multidimensional scaling (MDS) 分析結果亦發現親緣關係與時空變化之間沒有特定的關連性，表示日本鰻族群遺傳結構無論在時間或空間上皆無顯著差異。台灣地區的日本鰻柳葉期日齡顯著小於日本地區 (101.4 ± 9.0 天)，而台灣地區的早來游群柳葉期 (89.3 ± 8.3 天) 則與晚來游群 (92.4 ± 10.8 天) 無顯著差異 (p = 0.36)。三組不同柳葉期長短的鰻苗間並無顯著的遺傳分化現象 (FST = 0.0026, p = 0.11)，表示日本鰻之族群遺傳結構與柳葉期長短無明顯相關性。早來游群飼養在不同溫度下，體長與體重皆無顯著差異。而晚來游群的 31℃ 組，飼養六十天後，其體長顯著高於 25℃ 組，但體重無顯著差異。本研究結果支持台灣與日本地區之日本鰻應屬於逢機交配的單一族群，不同時空的日本鰻來游群可能並無南北群之分，而柳葉期的差異則可能是受到後天環境影響的結果，而非遺傳所致。
並列摘要
We use 6 polymorphic microsatellite loci and otolith increments to analyze population genetic structure and leptocephalus stages duration of Japanese eel from Taiwan and Japan between 2001 to 2002. We collected Japanese glass eel from Taiwan between 2007 to 2008 for growth experiment. In this study, we aim to clarify how the eel populations are distributed. Results showed very low genetic differentiation among recruits with insignificant differences (overall FST = 0.00015, p = 0.60). In multidimensional scaling (MDS) analysis, there are no specific spatial or temporal correlations between recruits, indicating no significant genetic differentiation in spatial and temporal scale. The mean larval durations of Japanese eel in Taiwan were significantly shorter than those in Japan (101.4 ± 9.0 d). The larval durations between early recruits (89.3 ± 8.3 d) and late recruits (92.4 ± 10.8 d) of Taiwan showed no significant difference (p = 0.36). There was also no significant genetic differentiation between samples with short or long larval durations (overall FST = 0.0026, P = 0.11), suggesting no correlation between larval duration and population genetic structure of Japanese eel. The mean total length and weight of early recruits, after 60 days culture, had no significant difference between groups reared at 25℃ and 31℃. The mean total length of late recruits reared under 31℃ is significantly longer than those reared under 25℃, but the mean weight under the two temperatures had no significant difference. Our results support the panmictic population of the Japanese eel. There may be no north and south populations between eels from Taiwan and Japan. The variation on length of leptocephalus stage is likely an acclimation, which depends on the environmental conditions, but not caused by heritability.