海拔对全缘叶绿绒蒿植株性状和花特征的表型选择分析

为了研究海拔差异对植株性状、花特征表型选择的影响，以青藏高原高寒草甸的全缘叶绿绒蒿（Meconopsis integrifolia）为研究材料，于盛花期内，测定不同海拔（4 452、4 081和3 681 m）种群中个体植株性状、花特征、单果结实数并进行统计分析，采用线性回归模型估计不同海拔种群间植株性状、花特征所受的表型选择（选择差与选择梯度）。结果表明：（1）随着海拔升高，全缘叶绿绒蒿植株性状、花特征及单果结实数显著降低，海拔越高的种群中株高越矮、叶面积越小、花数越少、花越小、单果结实数越低。（2）不同海拔种群中各性状的表型选择存在差异，较低海拔（3 681 m）种群中花数、花大小具有显著的选择差和选择梯度，表现为花越多、花越大的个体雌性适合度越高；海拔较高（4 081 m）的种群中株高、叶面积及花数更容易受到选择，表现为植株越高、叶面积越大、花越多的个体雌性适合度越高；海拔最高（4 452 m）的种群中叶面积与花数的选择梯度接近显著。（3）植物性状分化伴随着海拔的变化而呈现出差异，较低海拔种群中花特征容易受到选择，而较高海拔种群中可能由于传粉者稀少、资源限制等因素使得株高、叶面积更容易受到选择。

Phenotypic Selection on Plant Traits and Floral Traits at Different Altitudes for Meconopsis integrifolia

We measured plant traits and floral traits of Meconopsis integrifolia at different altitude populations (4 452 m, 4 081 m, 3 681 m), collected ripe fruits in the end of flowering and counted seed production per fruit to estimate the overall phenotypic selection differential and selection gradient. We used one way ANOVA analysis to estimate variations of plant traits, floral traits and seed production per fruit at different altitude populations. We evaluated phenotypic selection (selection differential and selection gradient) on plant traits (plant height and leaf size), floral traits at different altitudes populations using multi linear regression model. The results showed that: (1) there were significant reducing of plant traits, floral traits and seed production with the increasing altitude. The higher altitude, the lower plant height, the smaller leaf size, the lower number of flower per plant, the smaller floral size and the lower seed production per fruit were in population. (2) We found significant differences on phenotypic selection of plant traits and floral traits at different altitude populations. In particularly, there were significant selection differential and selection gradient on number of flower per plant and floral size in population 3 (3 681 m); however, plant height, leaf size and number of flower per plant were more likely to be chosen in population 2 (4 081 m); interestingly, selection differential and selection gradient on leaf size and number of flower per plant were marginal significant in population 1 (4 452 m). (3) Our results indicated that divergent altitudes might lead to different phenotypes, floral traits were more likely to be chosen at lower altitude. By contrast, plant height and leaf size were more likely to be chosen because of rare pollinators and resources limitation at higher altitude.