两种藨草属植物对盐度的表型可塑性反应

Phenotypic Plastic Response of two Scirpus Species to Salinity Gradient

表型可塑性是植物适应环境变化的一种重要方式.尽管有很多研究发现受到不同选择压力的物种间表型可塑性会发生分化,但常缺乏适合度证据以支持分化是否有适应意义.本研究比较了生于淡水环境的扁秆藨草和生于滩涂的海三棱藨草在0‰、5‰、10‰、15‰的盐度梯度下的营养生长和克隆繁殖的表现,发现所测量的9个性状中有7个性状的变化趋势在两个种间相似,且基于繁殖体数量和幼苗生生命力估计的相对适合度都随着盐度的增加而下降,但分株成活率和球茎数两个性状的变化在种间存在显著差异,相对适合度下降的速率也不同.这些结果表明虽然扁秆藨草和海三棱藨草响应盐度变化的表型可塑性变化是一致的,但后者更适应盐生环境.此外,成活率、繁殖体数量、总生物量这些常用的适合度代理性状与相对适合度的变化趋势不一致,提示应选择合适的性状来代理适合度.

Phenotypic plasticity is an important way for plants to adapt environment changes.Although many studies have reported that plant species in different habitats had different phenotypic plasticity,evidences of fitness to support their significant adaptation were lacked.This study designed four salinity gradients：0‰,5‰,10‰,and 15 ‰,to compare the performance of vegetative growth and clonal reproduction between Scirpus planiculmis from freshwater and S.mariqueter from seashore.The results showed：1）among of the nine traits investigated,the traits survival rate of ramet and tuber number were significantly different between the two species,whereas the other seven displayed similar plastic variations;2）their fitness of the two species estimated based on the number and viability of tubers both decreased with the increase of salinity,but they had different decrease rates.This differences may likely due to different tolerance ability of specific tubers.These findings suggest that the phenotypic plasticity in S.mariqueter has more adaptation significance than that of S.planiculmis.The common fitness agencies such as survival rate,propagule number,and total biomass showed different patterns,in comparison of the fitness estimated based on propagule number and offspring viability,hinting that it is essential to choose a proper agency to express fitness.