ON THE ECOLOGICAL AND EVOLUTIONARY SIGNIFICANCE
ON THE ECOLOGICAL AND EVOLUTIONARY SIGNIFICANCE
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论生态和进化意义
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Schuepp
中科院分区：
文献类型：
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作者：
L. M. In;S. K. Rice;P. Schuepp
在水生环境中，扩散性很低，CO2的有效性会限制植物的生长。自然选择倾向于减少二氧化碳扩散阻力的形态特征的假设通过来自Sphagnum属的三个系统发育独立的物种对（S. macrophyllum和S. strictum， S. portoricense和S. papillosum， S. trinitense和S. recurvum）进行了验证。水生物种（前者）和非水生物种（后者）在水下生长，并出现在一个普通的花园里，用于形式和功能的研究。水生类群具有相似的形态特征，包括更大、更薄、密度更低的枝叶和更多暴露在叶表面的光合细胞。三叶草枝、叶形态与边界层阻力的关系。在变速电化学流体隧道中，通过测量离子在镀镍模型上的扩散和对流来评估递归态对。在不同的流速和方向下，水生三棱棘鱼模型的边界层都比非水生反刍棘鱼模型薄。生长实验中碳的稳定同位素分析证实了流体隧道实验的结果。水生类群在水中生长时的6 - 13C值均低于非水生类群，但非水生的S. strictum因生长速率低而被剔除。这些结果表明，水生物种对二氧化碳吸收的总体抵抗力确实低于非水生物种。我们的观察表明，水生栖息地确实会选择对气体交换阻力较低的形态特征。
In aquatic environments diffusivity is low and CO2 availability can limit plant growth. The hypothesis that natural selection has favored morphological features that reduce resistance to diffusion of CO2 was tested using three phylogenetically independent species pairs from the genus Sphagnum (S. macrophyllum and S. strictum; S. portoricense and S. papillosum; and S. trinitense and S. recurvum). The aquatic (former) and the nonaquatic (latter) species were grown submerged and emerged in a common garden and used for studies of form and function. Aquatic taxa all had similar morphological features that included larger, thinner branch leaves arranged at lower densities and photosynthetic cells more greatly exposed at the leaf surface. The relationship between observed branch and leaf morphology and boundary layer resistance in the S. trinitenseS. recurvum species pair was assessed by measuring diffusion and convection of ions onto nickel-plated models in a variablespeed electrochemical fluid tunnel. For all flow speeds and orientations, the aquatic S. trinitense model had thinner boundary layers than the nonaquatic S. recurvum model. Analysis of stable isotopes of carbon from the growth experiment corroborated results from the fluid-tunnel experiments. The aquatic taxa all had lower 6 13C values when grown submerged compared to their nonaquatic pair with the exception of the nonaquatic S. strictum, which was removed due to low growth rates. These results indicate that aquatic species did experience lower overall resistance to CO2 uptake than nonaquatic taxa. Our observations suggest that aquatic habitats do select for morphological features that lower resistance to gas exchange.