COS 134-6 - CANCELLED - Role of phenotypic plasticity, selection, and transgenerational effects in the fine scale distribution of broad and narrow leaved Claytonia perfoliata (Portulacaceae)

Friday, August 12, 2011: 9:50 AM
13, Austin Convention Center
Patrick J. McIntyre, Population Biology Graduate Group, University of California Davis, Davis, CA
Background/Question/Methods: Among the factors that can cause associations between traits and the environments are environmentally induced plasticity and environment specific selection on fixed traits. I examine the role of selection and phenotypic plasticity, as well as transgenerational effects, on a striking shift in the frequency of linear and broad leaved morphs of a hexaploid annual plant, Claytonia perfoliata, over small spatial scales. Underneath the canopy of oak trees, 90% of C. perfoliata are broad leaved forms, while in immediately adjacent grassland habitat, broad leaved forms decline to less than 10% and linear leaved morphs dominate.  Using field transplants of broad and narrow leaved plants into canopy and grassland habitat over two years, I assessed the fitness of each morph across the two environments, selection on leaf traits, and transgenerational effects of maternal environment on leaf traits and fitness.

Results/Conclusions: Linear leaved forms produced up to 140% more seed in open habitat relative to broad leaved forms, while broad leaved forms produced up to 150% more seeds in shaded habitat. Phenotypic plasticity did not account for the differences in leaf shape amongmorphs, but did have a small effect on morph fitness across the two habitat types, with more plastic genotypes exhibiting slightly higher fitness across habitat types. Selection on leaf width varied among plots, but was generally positive in shaded habitat and negative in open habitat. A transgenerational effect was found for specific leaf area, with offspring of plants grown in shaded oak canopy environments having 10% higher values of SLA in shaded environments than offspring from plants grown in grassland habitat. Although plasticity and transgenerational effects may contribute to the distribution of leaf forms across environments, strong habitat-specific fitness differences appear to explain the association of morphs with the two environments.

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