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高寒退化草地狼毒繁殖性状的选择及其适应性

花匠小妙招
2024-12-18 01:42

摘要：

被子植物的繁殖性状在很大程度上被认为是通过传粉者介导的自然选择而进化。为了探究狼毒花性状的适应性，以天祝高寒退化草地狼毒为研究材料，通过检测其繁殖相关性状的选择差和选择梯度，探讨了该物种花表型的适应性及可能的选择机制。结果表明：单花序小花数和冠筒长具有显著的选择差和选择梯度（P<0.05），即受到正的定向选择作用；同时，两性状也检测到显著的非线性选择梯度（P<0.05），表现出稳定选择趋向。株高（即花序高度）受到负定向选择作用，其选择梯度为-0.102±0.039（P=0.008）；其他性状，如花冠口大小和单株丛花序数均未检测到显著的选择作用。总体表明，在该研究种群，狼毒的部分繁殖性状表现出适应性进化趋势，株高相对较矮、花筒较长和花序小花数较多的个体越有利于其适合度实现而受到选择。

关键词: 狼毒, 繁殖性状, 选择梯度, 适合度, 传粉

Abstract:

The reproductive traits of angiosperms are widely believed to have evolved largely through pollinator-mediated natural selection. The present study focused on Stellera chamaejasme, a dominant poisonous species in degraded alpine meadow in Tianzhu County of Gansu Province in China. S. chamaejasme was chosen as a model species to explore adaptation of floral traits and possible selective mechanisms by detecting their selection differentials and selection gradients. It was found that flower number per inflorescence and corolla tube length had both significant selection differentials and selection gradients (P<0.05), indicating positive directional selection for both traits. Also, significant nonlinear selection gradients (P<0.05) were detected for these two traits, possibly indicating stable selection occurring for them. Negative directional selection was detected for inflorescence length, with a significant linear selection gradient of -0.102±0.039 (P=0.008). No significant selection was detected for the other traits measured, such as corolla entrance size and inflorescence number per plant. In conclusion, the data indicate that some reproductive traits in S. chamaejasme exhibited a trend of adaptive evolution under natural selection, and individuals, which have relatively shorter inflorescence length, longer corolla tubes and more flowers per inflorescence, tend to be selected for due to their advantage in achieving reproductive fitness.

Key words: S. chamaejasme, reproductive traits, selection gradient, fitness, pollination