臺灣赤楊族群遺傳變異性之研究

Patterns of Genetic Variation of Alnus formosana in Taiwan

臺灣赤揚（Alnus formosana (Burk.) Makino），為落葉樹種，在臺灣地區分布很廣，由低海拔至中高海拔山區均有其蹤跡。本研究是利用澱粉膠體電泳探討臺灣赤楊二十二個族群之遺傳結構，共檢視十五種同功酵素，其中多型性基因座約佔59.1%，每一基因座之有效對偶基因數為1.21；族群間的歧異度為0.02，族群間的遺傳距離由0.000到0.019，平均為0.004。臺灣赤楊族群間分化的程度很低，可能是由於其花粉和種子均是靠風力傳播，以致族群間有大量的基因流傳而使遺傳變異性呈現均質化的分佈。此外，由實驗結果中發現有四個基因座其對偶基因的頻率與海拔梯度有顯著的相關性，顯示臺灣赤揚的遺傳變異性可能與高低海拔棲地的溫度差異有關。

Formosan alder (Alnus formosana (Burk.) Makino), a deciduous native tree in Taiwan, bas dominant colonizing ability in open areas from lowland up to 2,500 m. The genetic structure of twenty-two populations of this species was studied by allozyme electrophoresis analysis. In the fifteen enzymes surveyed, 59.1 % of the loci was found polymorphic and the mean effective number of alleles per locus 1.21. The proportion of genetic diversity among the populations studied was 0.02 and the genetic distance among populations ranged between 0.000 to 0.019 with a mean of 0.004. Low genetic differentiation in Alnus formosana may be attributed to high degree of gene flow. However, the significant correlations between allelic frequencies in four loci and the altitude gradient revealed partial genetic variation that correlated with temperature differences.