Allozyme Variations of a Widespread Tree Fern, Alsophila spinulosa (Hook.) Tryon (Cyatheaceae), in Taiwan

台灣廣泛分佈之樹蕨類植物台灣桫欏的同功酶遺傳變異

鄭育斌(Yu-Pin Cheng) ； 劉世慧(Shih-Hui Liu) ； 黃曜謀(Yao-Moan Huang) ； 陳建文(Chien-Wen Chen) ； 邱文良(Wen-Liang Chiou)

《台灣林業科學》 23卷1期 (2008/03) Pp. 21-34

https://doi.org/10.7075/TJFS.200803.0021

摘要

本研究利用同功酵素研究廣泛分佈於台灣的樹蕨類植物台灣桫欏(Alsophila spinulosa)的遺傳變異。測試6個酵素系統中，共獲得9個基因座(loci)和12個對偶基因(alleles)。分析各族群的遺傳歧異度，對偶基因平均數(A)為1.34，多型性基因座比率(P)為34.5%，異質結合度觀察值(H(下标 o))為0.145，異質結合度期望值(H(下标 e))為0.141。和其他蕨類或樹蕨類的遺傳歧異度平均值比較，台灣桫欏具有較高的遺傳歧異度。大的族群規模和配子體間的異交配育系統是造成台灣桫欏維持遺傳歧異度的重要原因。除此之外，部份的自交配育行為可能有助於單一孢子長距離傳播後的族群建立。以族群而言，南台灣的南仁山族群具有最高的異質結合度。經由孢子傳播進行的基因交流和廣泛分佈的特性，是台灣桫欏能維持族群間遺傳低度分化的重要因素。

關鍵字

同功酶變異 ； 台灣桫欏 ； 桫欏科 ； 台灣

並列摘要

Allozymes were used to detect the genetic diversity of Alsophila spinulosa, a widespread tree fern in Taiwan. Allozyme polymorphisms of 6 enzyme systems, including 9 loci and 12 alleles, were used to estimate the genetic diversity of A. spinulosa from 9 sites throughout Taiwan. The mean number of allele per locus (A) was 1.34, the percentage of polymorphic loci (P) was 34.5%, the observed heterozygosity (H(subscript o)) was 0.145, and the expected heterozygosity (H(subscript e)) was 0.141. The genetic diversity of A. spinulosa in Taiwan was higher than mean values of other diploid ferns and tree ferns. The large population size and an intergametophytic outcrossing mating system were thought to be important factors in A. spinulosa maintaining a higher level of genetic diversity. Inbreeding has also sometimes occurred, and this might have assisted the successful colonization by a single long-distance dispersal spore. At the population level, the Nanjenshan population (NJ), located in southern Taiwan, showed the highest expected heterozygosity (H(subscript e)). Additionally, lower levels of genetic differentiation among populations were detected and are thought to be a result of high gene flow due to spores.

並列關鍵字

allozyme variations ； Alsophila spinulosa ； Cyatheaeae ； Taiwan