摘要
对内蒙古中东部草原区分布的 11个大针茅 (Stipa grandis P. Smirn)地理种群进行了 RAPD分析。从 10 0个随机引物中筛选出 18个有效引物 ,共扩增出 2 2 1条 DNA带 ,多态性 DNA带 12 1条 ,占 5 4 .75 % ,平均每个引物扩增的 DNA带数为 12 .2 8条 ;特异性 DNA带 2 5条 ,占 11.31%。基于 Jaccard遗传相似性系数对此 2 2 1条 DNA带进行 U PGMA聚类分析 ,将 11个种群分为 3类 ,白音锡勒牧场的 8个种群聚为一类 ,林西种群和克什克腾种群两个种群聚为一类 ,阿巴嘎种群单独成为第 3类。用Mantel检验作进一步分析表明 ,在相对较大的尺度上 ,大针茅的遗传分化与地理距离相关极显著 (g>g0 .0 0 5) ;而在相对较小的尺度上 (白音锡勒牧场 8个种群 ) ,相关不显著 (g<g0 .0 50 )。特异性位点百分数与所处生境大于 10℃年积温及干燥度呈现极显著正相关 (p<0 .0 1)。对其中的 5个大针茅种群所在群落的植物组成、Shannon多样性指数以及重要值进行分析 ,发现这 5个种群的相似性系数矩阵与所在群落的相似性系数矩阵 (用重要值计算得到 )之间表现为显著正相关 (r=0 .770 3,g>g0 .0 5)。
Stipa grandis P. Smirn, an important perennial tussock grass in the Inner Mongolia steppe in China, is palatable for livestock and rich in nutrients, and is grazed by cattle and sheep at different stages of its growth cycle. Form. Stipa grandis is one of the major formations of the moderately-temperate steppe in Central Asia, and has considerable ecological and economic importance as it is not only suitable for grassland farming, but also provides an environmental defense for the Beijing-Tianjin area. Studies about Stipa grandis started in 1950's. The geographical distribution, growth and photo-physiological characteristics of Stipa grandis have been well documented, but molecular markers were used in the study of Stipa grandis in just recent years and documents are still lacking. In the present study, eleven sites were selected from the Form. Stipa grandis in the middle and eastern Inner Mongolia steppe. In each site, leaves of Stipa grandis plant were harvested for RAPD analysis, and at the same time, plant community investigation was carried out for five representative sites of the eleven. Eighteen oligonucleotides screened from 100 random decamer primers were selected to analyze the eleven populations of Stipa grandis, which produced profiles with intense and well-separated bands. A total of 221 bands were produced from the 18 selected primers with an average of 12.28 bands per primer, among which 121 bands were polymorphic. Twenty-five unique loci were obtained, accounting for 11.31% of the total amplified loci, and the percentage of unique loci was significantly correlated with aridity (r=0.76, P<0.01) and with cumulative temperatures above 10℃ (r=0.81, P<0.01) along the environmental gradient. Genetic distances between geographic populations of Stipa grandis ranged from 0.084 to 0.761, with an average of 0.243. A UPGMA dendrogram based on the genetic similarity coefficient matrix showed that the populations were most likely to be clustered if their geographic locations were nearer. A Mantel's test indicated that there was a significant correlation between the genetic distance and geographic distance (g>g_(0.005)) in a larger range containing all of the 11 populations. As for the 8 populations within the Baiyinxile Farm, there was no correlation between genetic distance and geographic distance (g<g_(0.05)), which was consistent with the results of the dendrogram. It may be reasonable to suggest that rainfall and temperature were the major factors that affected genetic differentiation of Stipa grandis on a larger scale (about 240km), and that on a smaller scale (below 50km) where the variation of rainfall and temperature was not significant, a combination of several environmental factors was responsible for the genetic differentiation of Stipa grandis populations. The composition, species frequency and importance value, and Shannon's index of five communities differed from each other. The similarity between communities were computed using the Pearson correlation method based on the importance values of the species and a dendrogram based on the similarity coefficient matrix was constructed using UPGMA in NTSYS-pc. This dendrogram was similar to the one that was established using the corresponding populations of Stipa grandis based on RAPD data. Further analysis with Mantel's test indicated that there was a positive correlation (r=0.7703, g>g_(0.05)) between the similarity coefficient matrix of the five Stipa grandis populations and that of their communities.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第10期2178-2185,共8页
Acta Ecologica Sinica
基金
国家重点基础研究发展规划资助项目 ( G2 0 0 0 0 1860 1)~~
关键词
大针茅
地理种群
遗传分化
RAPD
Mantel检验
环境因子
重要值
Stipa grandis
geographic population
genetic differentiation
RAPD
Mantel's test
environmental factor
importance value
