Groff, Dulcinea V. , Noyes, Richard D. .
Geography and phylogeny of sexual and apomictic Erigeron tenuis (Asteraceae).
The geographical and evolutionary relationship between sexual populations of Erigeron tenuis and E. strigosus is explored. Erigeron tenuis is the presumed sister species to E. strigosus and previous chromosome counts suggest that it comprises diploid and polyploid populations. Analyses of pollen grains from 530 herbarium specimens are used to estimate the distribution of diploid and polyploid populations. The analyses reveal that diploids are restricted to Eastern Texas while polyploids are widely distributed. This pattern is consistent with distributions in other apomictic complexes. Chromosome counts confirm 2n = 18 for plants collected from a sexual population while counts for polyploids from two populations reveal 2n = 27. Ovule development of sexual diploid E. tenuis is tetrasporic and diplosporous for two polyploid populations. To explore the relationship between diploid E. tenuis and diploid E. strigosus, the ITS and ETS spacer regions of nuclear ribosomal DNA are used to construct a phylogeny. The phylogenetic analysis nests E. tenuis within E. strigosus, which implies that E. strigosus is paraphyletic. This result has implications for our understanding of apomixis in the group.
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1 - University of Central Arkansas, Department of Biology, 180 Lewis Science Center, Conway, Arkansas, 72035, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 9:30 AM