合歡山區玉山箭竹族群之類黃素變異及遺傳結構

Abstract

玉山箭竹為台灣原產之竹亞科植物，於海拔1500至3500公尺有廣泛分布， 然依海拔及生態棲地環境之不同在表現型上有極大之變異，此種表現型變 異是否有遺傳基礎﹖我們研究玉山箭竹之三個不同海拔及兩種不同生育環 境的採樣點，經歸群分析及主成份分析之結果皆顯示類黃素組成並未依海 拔高度之不同而分化，卻依生育環境之不同而有分歧化的現象，類黃素組 成分化的原因可能並非純由表現型可塑性所造成，遺傳分化可能也是造成 類黃素組成分歧化的原因之一。而遺傳變異和樣點間遺傳分化的程度利用 澱粉膠體電泳技術加以分析；總共分析15種酵素系統合計24個基因座 (loci)，其中20個基因座為多形性(99%標準)。當以99%為多形性標準時， 多形性基因座百分比分別為66.7%。利用F-statistics 和遺傳歧異度分析 樣點內及樣點間遺傳變異所佔的比例， 估計樣點間的變異佔總變異量 的 6.8%，其餘93.2%存在樣點內，基因流傳評估值(Nm)為3.426，結果顯 示族群間的基因交流缺乏有效的阻隔，此乃由於樣點間呈連續性的分布， 缺乏地理阻隔所致，但由Fst及Gst值為 0.068來看，已具有某種程度的分 化。根據遺傳距離進行的歸群分析及一種座標法分析的結果顯示，各樣點 已有分群趨勢，分群的情形和類黃素的結果有高度的吻合，顯示玉山箭竹 遺傳結構有隨生育地環境而分化的趨勢，此可能與生育地的選擇壓力有關 。

Yushan cane(Bambusoideae)is a native species of Taiwan.It is widely distributed from 1,500 to 3,500 above sea level in Taiwan .It shows great phenotypic variability in different habitats.The flavonoid data of six sites at 3 different altitudes and 2 different kinds of habitates were used in a cluster analysis and a principle component analysis. The results of cluster analysis and principle component analysis indicate that flavonoid compos- ition diversifies according to habitates.Genetic variation were investigated using isozyme starch gel electrophoresis.A total of 15 enzyme systems and 24 loci were studied.Twenty out of 24 loci examined were polymorphic(99% criterion).The average proporation of polymorphic loci per site was 66.7% at the 99% criterion for polymorphism,F-statistics and gene diversity analysis,the result indicated that 6.8% of variation were distributed among sites. The estimate of gene flow (Nm) was 3.462, indicating high gene flow among sites. The Fst and Gst of 0.068 indicated that there was certain degree of diversificaton among sites.The results of a cluster analysis using Taxonomic distance matrix and a non- metric multidimensional analysis showed that, there was a tendency of grouping according to habitats.