筆筒樹是蕨類植物的一種，屬於欏科(Cyatheaceae)。主要分布在
亞洲大陸邊緣的島嶼上如臺灣、琉球、菲律賓。臺灣位居這一個島弧的中
點，這個島上的筆筒樹族群結構自然值得深入研究。本研究旨在檢視臺灣
各地區筆筒樹的亞族群遺傳結構情形。總共檢查十八個亞族群，十三種同
功酵素，包含十六個基因座。各採樣點的平均族群遺傳變異度理論值(HE)
為0.057，範圍介於0.050-0.063之間，實際觀測值(HO)為0.064，範圍介於
0.035-0.082之間，總遺傳變異度(HT)為0.064，範圍介於0.020-0.108之間
。多型性基因座的比例為12.5%。平均每一基因座有1.1個對偶基因，而每
一基因座的平均有效對偶基因數為1.07。利用F-統計分析結果，亞族群內
自交係數FIS=-0.157顯示此種植物偏好配子間雜交。亞族群間變異度的指
數FST=0.039，說明了亞族群間並無遺傳分化，基因流傳率大(Nm=6.16)。
亞族群間遺傳距離很小(0-0.015)，和地理距離不相關。諸此顯示亞族群間
的基因流傳缺乏有效地理阻隔，各亞族群間基因流傳非常充分。這樣的結
果說明了普遍存在於臺灣各地的筆筒樹，亞族群間是沒有分化的。

Sphaeropteris lepifera (Hook.) Tryon is one of the species of
tree ferns distributed along the islands arch in eastern Asia,
such as Taiwan, Ryukyu archipelago and the Philippines. Taiwan
located in the center of the island arch, it is naturally worthy
of studying the genetic structure of this fern. The major
destination of this study is to assess the pattern of genetic
variation in subpopulations of tree fern Sphaeropteris lepifera
(Hook.) Tryon in Taiwan. Eighteen subpopulations were surveyed
by using starch gel electrophoresis methods. Sixteen loci of 13
isozymes were detected. The mean expected herterozygosity(HE)
was 0.057 and ranged from 0.05 to 0.063. The mean observed
heterozygosity(HO) was 0.064 and ranged from 0.035 to 0.082.
The total heterozygosity(HT) was 0.064 and ranged from 0.02 to
0.108. The percentage of polymorphic loci(P) was 12.5 for
polymorphism. On average, the number of alleles per locus (AP)
was 1.1 and the effective number of alleles per locus(AE) was
1.07. F-statistics revealed that the inbreeding coefficient
within subpopulations(FIS) was -0.157. This negative value
suggest that the species preferred intergametophytic outcrossing.
The level of genetic differentiation among subpopulations(FST)
was 0.039. It showed that the level of genetic differentiation
among subpopulations was very low. Gene flow rate among
subpopulations was far greater than one (Nm=6.16) and genetic
distance is very small ranged from 0 to 0.015, moreover, genetic
distance between subpopulations did not correlate to the
geographical distance. All these results indicated a lack of
barriers to gene flow among subpopulations, thus there is no
genetic differentiation among subpopulations of Sphaeropteris
lepifera (Hook.) Tryon in Taiwan.
Sphaeropteris lepifera (Hook.) Tryon is one of the species of