Burns, Jean .
Maternal environment influences the production of a seed size hetermorphism in the weedy species Murdannia keisak (Commelinaceae).
SEED hetermorphisms can have important effects on dispersal capabilities, germination, and seedling survival and may be important for species that disperse into disturbed habitats and experience spatial or temporal variation. I report for the first time a seed size hetermorphism in the weedy plant, Murdannia keisak. In a greenhouse experiment, seeds of Murdannia keisak produced in the proximal end of the locule were approximately 2 times larger than those produced distally in the locule. Field observations also found significant differences between proximal and distal seeds and additional seed size variation among distal seeds. Maternal environment in the greenhouse experiment influenced the magnitude of seed size differences, with plants in low-nutrient environments exhibiting the greatest difference between seed types, and plants in high nutrient environments producing seeds that did not differ significantly in size. The position of the seed in the locule, the maternal environment, and the interaction between position and maternal environment all influenced germination proportions, suggesting fitness consequences, not only for the seed hetermorphism, but potentially for plasticity in the degree of hetermorphism as well. It is possible that the observed plasticity in seed size hetermorphism has adaptive implications, particularly for species that occur across environments with differing levels of environmental variation.[c.e.:srb]
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1 - Florida State University, Department of Biological Sciences, Tallahasse, Florida, 32306-1100, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 10:15 AM