珍稀濒危植物海南粗榧种群遗传多样性研究

利用RAPD技术对珍稀濒危植物海南粗榧（Cephalotaxus manniiHook.f.)遗传多样性水平，分布、濒危原因及物种保护等问题进行了探讨。结果表明：1、海南粗榧在海南岛的5个取样地点表现出低水平的遗传多样性，对环境变化物适应能力不强；2、海南粗榧种群内和种群间的遗传多样性所占比例有很大差异，绝大部分变异分布于种群内（DAN多样性为85.1%)；种群间仅有较低程度的分化；3、人为砍伐，植被破坏，台风、被食用遗传漂变是海南粗榧遗传多样性低水平的主要原因，也是物种濒危的主要原因；4、对于呈零星分布的濒危植物海南粗榧的研究与保护，应充分考虑个体小环境之间的差异。考虑影响小种群的随机因素；5、应采取有力措施，就地保护现有种群，并寻求适当的方法迅速扩展种群，降低基因丧失率；选择遗传多样性较高且破坏相对较小的黎母岭种群作为保护重点；同时应加强对其他种群的保护与管理；6、海南粗榧种群内，种群音质遗传多样性在不同引物之间有较大差别。多态性位点百分率则是种群间的变化大于引物间的变化。

Genetic Diversity of Cephalotaxus mannii, a Rare and Endangered Plant

Using RAPD technique, the DNA diversity of Cephalotaxus mannii Hook. f., its genetic diversity pattern, the reasons for its endangered position and conservative approaches were studied. The results show that: 1. The genetic diversity of C. mannii collected from five localities in Hainan is low, and its adaptability to environmental change is weak. 2. The differences of genetic diversity between intra- and inter-populations are great, and the major variation distributes within the population (DNA diversity is 85.1%). 3. The excessive lumbering, man-made destruction, violent typhoon, edible value of the seeds and genetic drift were the main reasons for the low-level genetic diversity of C. mannii and its endangered position. 4. The difference of the micro-environment and other random factors affecting the population should also be taken into full consideration in the study and in protection of such occasionally scattered plants. 5. Enforced measures should be taken to protect the present population, enlarge the population and lower the loss rate of its gene. Mt. Limulin should be chosen as a conservative spot because of its high genetic diversity and less destruction of the forest. Meanwhile, the protection of other populations should be enforced. 6. The differences within and between the populations are great based on different primers used. The change of proportions in polymorphic loci between the populations is more than that between the primers.