新疆北部拟南芥自然居群表型变异与协变

拟南芥(Arabidopsis thaliana)自然居群的表型特征代表其在自然环境下的适应状况, 不同居群间特征的对比可以为了解拟南芥表型变化规律, 进而分析其形成过程和机制提供重要线索。本研究以分布于新疆北部天山、塔尔巴哈台山和阿尔泰山的10个种群的9个表型性状为基础, 对比分析了小尺度、局域尺度和区域尺度环境下原生境拟南芥种群表型性状的变化。结果发现, 不同性状对环境变化的反应不同, 其中株高、株重、根重、根长、单个果实重、果实开裂力度在3种环境尺度下种群间的差异均达到极显著水平, 而分枝数、果实长度的种群间变化不显著, 种群间的表型分化系数较低。不同环境尺度下株重、根重、单株果数均表现出一致的协变格局, 反映了生理功能性状之间整合对拟南芥适应环境的重要性。同时, 各种群间整体的性状协变差异性明显, 根长、单个果实重、分枝数、果实长度、果实开裂力度等特征与其他特征协变具有明显的局部性, 局域尺度和区域尺度环境之间的变化较大。聚类分析发现区域尺度上的不同种群聚合在一起的现象非常突出, 进一步表明拟南芥的表型特征受微环境的强烈影响。Mantel检验表明, 小尺度上10个种群株高、株重、根重、单个果实重、果实长度、果实开裂力度6个性状变化存在显著的空间相关性, 而分枝数、根长的相关性却不显著。因此, 我们认为拟南芥表型变化受小尺度环境的影响强烈, 但在表型层面并非所有性状都与原生境气候存在遗传关联。

Phenotypic Variation and covariation among natural populations of Arabidopsis thaliana in North Xinjiang

Phenotypic traits of the natural Arabidopsis thaliana population represent its adaptation in natural environments. Comparison of phenotypic traits among different populations can provide important clues for understanding phenotypic variation and formation processes of A. thaliana. It is an important aspect that cannot be ignored for phenotypic adaptation and evolution of natural A. thaliana populations. We investigated nine phenotypic traits of 10 A. thaliana populations located in the northern Tianshan, Altai, and Tarbagatay mountains of Xinjiang, and compared variations in phenotypic traits in natural conditions at micro-, local- and regional-scales. Our results showed that different traits respond differently to environm- ental changes. Plant height, plant weight, root weight, root length, single fruit weight and fruit dehiscence force differed among populations at the three scales. However, branching number and fruit length did not differ among populations with low phenotypic differentiation coefficients. Plant weight, root weight and fruit number per plant all showed a consistent integration pattern at different scales, potentially reflecting the importance of physiological functional integration in A. thaliana. These three phenotypic characteristics also exhibited obvious adaptation to local environment. At the same time, we found that the extent of integration of phenotypic traits varied between local and regional scales. Cluster analysis showed that different populations from the same region grouped together, further showing that the phenotypic traits of A. thaliana were strongly influenced by the micro-scale environmental factors. Mantel test showed that the variations of plant height, plant weight, root weight, single fruit weight, fruit length and fruit dehiscence force significantly correlated with geographic distance, while the variations of branch number and root length did not. We therefore concluded that phenotypic variations of A. thaliana were strongly affected by the micro- scale environmental factors. However, not all the phenotypic traits were associated with the original habitat climate.