中文摘要：

借助随机扩增多态DNA方法，分析了中国特有的濒危植物长叶榧的遗传多样性和遗传分化．结果表明：12个随机引物在9个长叶榧自然群体180个样品中可检测到180个可重复位点，其中多态位点119个．长叶榧物种水平的遗传多样性较高，多态位点百分率（P）为66．11％，Shannon信息指数（，）为0．3087，Nei指数（h）为0．2015；而群体水平的遗传多样性较低，P、I和h分别平均为23．76％、0．1221和0．0813．AMOVA分子变异显示，42．57％变异来源于群体内，57．43％变异来源于群体间，群体间的遗传分化系数（Gst）为0．5965，群体间的遗传分化程度高．长叶榧群体间的基因流很低，为0．3382．瓶颈效应、群体隔离和群体间基因流低等因素都加剧了长叶榧群体间的遗传分化．9个长叶榧群体间的平均遗传距离为0．1630．通过UPGMA进行聚类，可将9个长叶榧群体分为浙江和福建两大类群．建议在迁地保护时应尽量避免在群体之间实施种质迁移．

英文摘要：

With random amplified polymorphic DNA （RAPD） techniques, this paper studied the genetic diversity and genetic differentiation of Torreya jackii, an endangered plant endemic to China. In the 180 individuals of 9 T. jackii natural populations, 180 repetitive loci were detected by using 12 random primers, among which, 119 were polymorphic. At species level, the percentage of polymorphic loci （P） was 66. 11%, and the genetic diversity estimated by Shannon information index （I） and Nei＇ s index （h） was 0. 3087 and 0. 2015, respectively, suggesting that the genetic diversity at species level was relatively high. However, at population level, the genetic diversity was relatively low （ P = 23.76%, I = 0. 1221, and h = 0. 0813 ）. The analysis of molecular variance （AMOVA） showed that 42. 57% of genetic variance was found within populations, and 57.43% of it was resided among populations. The coefficient of gene differentiation （Gst） was 0. 5965, indicating the high genetic differentiation among the populations of T. jackii, and the gene flow among the populations was quite low, being 0. 3382. The bottleneck effect, population isolation, and low gene flow among populations would have contributed to such a population genetic structure in T. jackii. The averaged genetic distance among 9 T. jackii populations was 0. 1630. By using the unweighted pair group method with arithmetic mean （UPGMA）, the 9 populations could be divided into two groups, i. e. , Zhejiang group and Fujian group. It was proposed that in the ex situ conservation of T. jackii, the germplasm transferring among populations should be avoided.