Systematics/Phytogeography / Taxonomie/ Section
Oberle, Brad J. , Esselman, Elizabeth .
Relative fitness of apparent hybrids suggests dynamic ploidy evolution in Eastern Dodecatheon (Primulaceae)..
Two species of Dodecatheon with contrasting range sizes, ecologies and ploidy levels grow in parapatry in southern Illinois. D. frenchii is a rare diploid that is endemic to shaded sandstone cliffs. D. meadia is a widespread tetraploid that often grows in exposed cliff-top glade habitats situated directly above populations of D. frenchii. Despite the difference in ploidy, plants with intermediate morphology sometimes grow in intermediate microhabitats, suggesting hyrbidization. We characterized the morphological intermediacy of plants from one such population using established infructescence characters and new microscopic seed characters. We also investigated the potential for gene flow among taxa by estimating different fitness components for morphologically intermediate population relative to typical populations. Contrary to the expectation for hybrids between plants with different ploidy levels, morphologically intermediate plants showed higher fertility rates than typical populations, and similar fecundity to D. frenchii. These results, together with previous cytological work and preliminary molecular data suggest that polyploid evolution is ongoing in this group, although the direction is unclear.
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1 - Washington University, Department of Biology, Campus Box 1137, One Brookings Drive, St. Louis, Missouri, 63130-4899, USA
2 - Southern Illinois University, Department of Biological Sciences, Box 1651, Edwardsville, Illinois, 62026-1651, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Room 5/Woodward
Date: Tuesday, July 29th, 2008
Time: 2:45 PM