Dissertation Research: Ecology and Evolution of Aquatic Sphagna: Functional Morphology, Physiology and Phylogeny

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Large boundary layers and slow diffusion rates of dioxide in water can lead to limitations in growth and photosynthesis of aquatic and saturated plants. Although investigators have sought to characterize the physiological mechanisms that facilitate carbon uptake in water, little work has focused on the role of morphology in reducing boundary layer resistances in aquatic habitats. Species in the moss genus Sphagnum exhibit morphological variation that preliminary studies indicate is correlated with position along the water gradient. Thus, the genus can be used as a model system to investigate the relationship among morphology, boundary layer properties and physiological ecology. Also, because the genus is taxonomically well studied phylogeny can be developed and modern methods of comparative biology used to test hypotheses of adaptation. The major goals of this proposed study are as follows: 1) to determine the extent that morphology and habitat are correlated in Sphagnum; 2) to measure boundary layer conductance for plants along the water gradient and describe its relationships to morphology; 3) to demonstrate that differences in boundary layer conductance lead to carbon limitations for non-aquatic Sphagnum at submerged CO2 levels; and 4) to test whether functional characters are adaptations using historical evidence from a constructed phylogeny.