中文摘要：

将从天山北部不同地理区域采集的7个拟南芥种群在同质园中种植，研究干湿2种处理下不同种群的表型分化特点及其自然选择特征，分析拟南芥在不同地区表型分化的可能机制。结果表明：实验观测的株高、株高／根长、分支数等9个特征在种群间差异显著，其中分枝数、果实总数、株高／根长、成熟时间以及间隔时间5个特征在交互作用下呈现出显著差异。聚类分析发现2种处理下都将干旱地区种群归为一类，湿润地区的种群归为另一类，种群间特征的多重比较结果也进一步证明了这一点。回归分析结果表明，无论干旱还是湿润处理，自然选择对拟南芥各种群的株高、分枝数、莲座叶大小、株高／根长、叶片数等特征的选择均定向增加；干旱处理下，对额敏种群的开花物候的选择定向减小，而湿润条件下对青河2繁殖时间（间隔时间）的选择则为定向增加。总结认为：天山北部拟南芥种群间株高、分枝数、株高／根长、果实总数、开花时间、成熟时间、间隔时间、莲座叶大小和开花时叶片数已经发生了遗传特化，降水是其发生的主要环境因子，自然选择是种群间表型分化主要动力，但不排除地理隔离的因素作用。

英文摘要：

We planted the seeds of seven populations from different geographical regions in northern Tianshan in the common garden,and set the wet and dry treatments. In order to investigate the characteristics of the phenotypie differentiation and the trend of natural selection in different populations, analyzing possible mechanism that phenotypic differentiation of Arabidopsis thaliana in different regions. The results show there are nine characteristics of experimental observations have significant differences among populations,including shoot height,branch number, number of fruits and so on. Of which five features are branch number, number of fruits, shoot height/root length, time to maturation and interval days respectively, in the interaction showed significant differences. Cluster analysis found that populations of arid regions classified as a class,wet populations classified as another group under dry and wet treatment both are. Multiple comparisons between the characteristics of populations further proved this point. Regression analysis showed that both dry or wet treatments, natural selection of plant height, branch number and other features among populations in Arabidopsis thaliana was directed to increase; dry treatment, to the choice of Emin population＇s flowering phenology is directional reduce, however, to natural selection of Qinghe2 breeding time （the interval in days） was directed to increase under wet treatment. The conclusion is that shoot height, branch number, number of fruits, shoot height/ root length, rosette size, time to flowering, time to maturation, interval days and leaf number at flowering have occurred genetic specialization among populations of Arabidopsis thaliana in northern Tianshan Mountains,precipitation is the main en- vironmental factors of its occurrence, natural selection is the main driving force of phenotypic differentiation among populations.