Allozyme variations in Michelia formosana (Kanehira) Masamune(Magnoliaceae), and the inference of a glacial refugium in Taiwan
Allozyme variations in Michelia formosana (Kanehira) Masamune(Magnoliaceae), and the inference of a glacial refugium in Taiwan
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含笑正宗（木兰科）同种酶变异与台湾冰川保护区的推论
DOI：
10.1007/s001220051666
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发表时间：
2001
影响因子：
5.4
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
T.
摘要台湾含笑在台湾全岛分布，在日本琉球群岛也有分布。利用5个酶系统的Pgm-1、Idh-1、Mr-1、Skdh-1和Ppo-3多态性位点对台湾木兰等位酶遗传变异进行了研究。描述种群内变异的期望杂合度（He）平均值为0.241。总体Fis（0.0736）表明在群体水平上杂合子明显缺乏。该阳性率主要来自北纬平林、赤石、五峰和琉球的种群，也与Ppo-3位点有关。在群体间变异中，Fst占总杂合度的10.6%，与零偏差显著。这种种群分化与动物异交的一般热带木本物种很好地吻合。兰屿种群与台湾本土植物在形态上存在一定差异，但未在非加权对群聚类分析中反映出来。然而，Pgm-1d是蓝屿上生长的植物的诊断特征，因为它在所有其他台湾木属居群中完全没有。本研究中约18%的等位基因表现出临床地理变异，并被发现与整个物种范围的纬度梯度显著相关。然而，这不是一个线性关系，而是一个具有峰值形式的曲线，这与种群的期望杂合度与纬度之间的关系完全相同。这一观察结果表明，台湾中部的南投县可能是台湾紫杉树遗传多样性的冰川避难所。对台湾7种分布较广的植物的研究结果也支持上述推论。这个冰川避难所的位置可能与数百万年前中央山脊的首次出现有关，中央山脊自然成为接收亚洲大陆遗传多样性的主要窗口。
Abstract Michelia formosana is distributed islandwide in Taiwan and also occurs in the Ryukyu Archipelago, Japan. Allozyme genetic variability in M. formosana (Magnoliaceae) was investigated using five polymorphic loci (Pgm-1, Idh-1, Mr-1, Skdh-1, and Ppo-3) from five enzyme systems. The average value of expected heterozygosity (He) describing within-population variation was 0.241. The overall Fis (0.0736) indicates a significant deficiency of heterozygotes at the population level. This positive value of Fis is mainly contributed from populations found at Pinglin, Chienshi, Wufeng, and the Ryukyus, all located at northern latitudes, and is also caused by locus Ppo-3. Among-population variation, Fst, accounted for 10.6% of the total heterozygosity and deviates significantly from zero. This populational differentiation agrees well with that of general tropical woody species outcrossed by animals. The population on Lanyu (Orchid Island) has some morphological differences from the plants native to Taiwan, but this was not reflected in the cluster analysis using the unweighted pair group method. Pgm-1d, however, is the diagnostic characteristic for the plants growing on Lanyu as it is entirely absent from all other populations of M. formosana. About 18% of the alleles of this study show clinal geographical variation and were found to be significantly related to latitudinal gradients throughout the species range. This, however, is not a linear relation but a curve with a peak form which is exactly the same as the relationship between expected heterozygosities of populations and latitude. This observation suggests that Nantou County, in central Taiwan could be a glacial refugium for genetic diversity of M. formosana. This inference is further supported by analysis of published studies on seven widely spread plant species in Taiwan. Location of this glacial refugium is probably related to the first emergence of the Central Mountain Ridge millions of years ago that naturally becamed the major window to receive genetic diversity from the Asian mainland.