Systematics/Phytogeography / Taxonomie/ Section
Hertweck, Kate L. , Pires, J. Chris .
Evolution of Tradescantia: Combining chromosomal evolution, biogeography, morphology, and phylogeny.
The Tradescantia alliance (wandering jews, spiderworts) is a group of ten genera that exhibit a wide variety of mechanisms of chromosomal evolution, including polyploidy, hybridization, and chromosomal restructuring. These genera include about 130 species from the New World occupying a wide variety of habitats and exhibiting considerable morphological complexity. This study analyzes morphological, cytogenetic, and biogeographic information in the context of a molecular phylogeny to determine the extent and effects of chromosomal changes in the Tradescantia alliance. Systematics of Commelinaceae are challenging primarily because flowers in the group are deliquescent and floral characters are not preserved in herbarium specimens. Also, morphological characters are confusing and seem to have arisen via convergent evolution and interspecific hybridization appears quite common. Chromosomal changes are immensely important to ecological adaptation and species evolution in both plants and animals. A thorough examination of chromosomal evolution in New World Commelinaceae is essential in understanding how chromosomal variation affects biodiversity across geographic ranges on an evolutionary timescale. Preliminary chloroplast and nuclear data suggest that a suite of characters (chromosome number, morphology, etc.) will be required to circumscribe genera. Relationships between nuclear alleles from the same species indicate possible hybridization, and chromosomal changes in some groups are associated with changes in growth habit or habitat preference.
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1 - University of Missouri, Biological Sciences, 1201 East Rollins Road, 311 Life Sciences Center, Columbia, MO, 65211, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 1:15 PM