Developmental and Structural Section
Walls, Ramona , Geeta, R .
Leaf venation and the relationship between form and function in Dioscorea.
THERE is wide variation in leaf form within the Dioscoreaceae, as in many plant families. If this variation is a result of ecological divergence and natural selection, then it should relate to variation in leaf function. On the other hand, if evolutionary history drives patterns of leaf form, then we should see strong phylogenetic, rather than ecological, signals. We examined the relationship between leaf structure and function in fifteen species from across the genus Dioscorea, with emphasis on venation and the functions supported by veins. We grew plants in a greenhouse and measured morphological traits such as leaf size and shape, specific leaf area, primary vein density and arrangement, minor vein density, stomatal size and index, and mesophyll characteristics, as well as functional traits such as maximum photosynthetic rate, hydraulic conductance, and tensile strength. Because leaf function is determined by the coordinated interaction of many morphological and physiological traits, we examine both bivariate and multivariate relationships among traits. We find that the relationships among leaf venation architecture and other aspects of leaf morphology suggest strong morphological integration as well as possible constraints or trade-offs. The relationships among morphological traits and function are more variable, as expected, because some functional traits, like photosynthetic rate, are under strong physiological regulation, while others, such as physical strength or hydraulic conductance, depend more on structure. Multivariate descriptions of leaf form that consider both physiological and morphological traits show no phylogenetic conservatism at this taxonomic scale, although some individual morphological traits appear to be conserved. The importance of variation in leaf form and function for plant responses to the environment will be discussed.[c.e.:srb]
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1 - Stony Brook University, Ecology and Evolution, 650 Life Sciences Building, Stony Brook, New York, 11794-5245, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 312/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 10:15 AM