Abstract

Polyploidization is a significant mode of speciation in plants. Polyploids often occupy habitats different from those of their diploid parents. In Taiwan, two varieties of Pteris fauriei, one diploid and one triploid, have been identified. The number of spores per sporangium and the size of spores are reliable indicators of ploidy. Diploid P. fauriei have 64-spore sporangia and the spores are significantly smaller than spores of triploid plants, which have 32-spore sporangia. Based on these findings, the distribution and habitats of the two cytotypes in Taiwan are characterized from both living plants and herbarium specimens. Altogether, 516 live plants from 32 locations and 76 herbarium specimens were analyzed. In general, diploid plants occur in warmer habitats than triploid plants. Diploid plants are widely distributed in Taiwan and nearby islands, but do not occur in central Taiwan nor in the Matsu islands. In contrast, triploid plants are not found in southern tip of Taiwan nor on islands west of central Taiwan. In northern Taiwan and on the west-central islands, diploids grow most often in exposed sites and grasslands. However, in southern Taiwan and islands Lanyu and Lutao, diploids also occur in woodlands. Triploids are restricted to grassland and woodland habitats in Taiwan, but grow in exposed sites, grassland and woodland habitats in Matsu islands. In general, triploids grow at higher elevations than the diploids.

中文摘要

多倍體化為植物種化之重要模式之一，多倍體棲地類型通常與它們的二倍體親本有所不同。在臺灣，傅氏鳳尾蕨 (Pteris fauriei) 已被證實具有二倍體及三倍體兩個變種，而孢子囊內孢子數及孢子大小為判斷倍體數的可信依據，二倍體植株孢子囊內孢子數64且孢子顯著小於三倍體植株，而三倍體植株孢子囊內孢子數則為32；基於這些發現，藉由新鮮植株及標本館標本，檢視臺灣地區此二核型的分布及棲地分布。從32 族群的516株新鮮植株及76 份標本館標本資料顯示，二倍體植株通常較三倍體植株生存在較溫暖的棲地，二倍體植株廣泛分布於臺灣本島及鄰近島嶼，但未出現在臺灣本島中部地區或臺灣北方的馬祖島嶼，相對地，三倍體植株則未在臺灣南端或臺灣中部的西側島嶼被發現。臺灣本島北部及中西側島嶼，二倍體植株最常生長在開闊地及草生地，然而，臺灣本島南部及東南側的島嶼，二倍體植株也在林地出現；臺灣本島三倍體植株侷限分布於草生地及林地，但在馬祖島嶼的開闊地、草生地及林地均可發現其蹤跡。除此之外，三倍體植株一般較二倍體植株具有較高的海拔分布。

Keyword: Diploid, cytotype, distribution, habitat, Pteridaceae, Pteris fauriei, triploid, Taiwan, 二倍體, 細胞型, 分布, 棲地, 鳳尾蕨科, 傅氏鳳尾蕨, 三倍體, 臺灣.