Diazgranados, Mauricio , Barber, Janet C. .
Reconstructing the phylogeny of the frailejones (subtribe Espeletiinae, Asteraceae) with multiple molecular markers: a preliminary assessment.
The frailejones (Espeletia complex, subtribe Espeletiinae Cuatrec., Asteraceae: Heliantheae) are a model system to study rapid adaptive radiations, speciation mechanisms, population genetics and impact of climate change in sky islands. These endemic plants of the forests and páramos of Colombia, Ecuador and Venezuela are of critical ecological importance. Evidence suggesting a rapid radiation include a large number of species (ca. 140 spp. in eight genera), a recent origin (< 2-4 my BP), and a broad spectrum of morphological features. Although there have been some previous attempts to reconstruct its evolutionary history, relationships among genera and species remain largely unresolved. We are reconstructing the phylogeny for the group, ultimately to test the monophyly of each genus and to review and revise the classification of the group. To date, ten molecular markers (three nuclear regions: ITS, ETS and GapC; and seven chloroplast regions: rpoB- trnY, ndhC-trnV, trnL-rpl32, rpl-16, rps-16, ycf6-psbM and trnG) have been amplified for ca. 20 taxa. In total, 10,229 base pairs (bp) were amplified, yielding 215 informative characters (2.1 %). Phylogenetic reconstructions from total evidence suggest that none of the polytypic genera within the complex is monophyletic. The molecular phylogeny shows strong support for the monophyly of the Espeletia complex, but only low to moderate support for remaining internal nodes. Interestingly, the tree shows some geographic structure, with one clade containing only Venezuelan species and another clade comprising Colombian species. A phylogeny based on nuclear data only shows identical results. Despite the notorious morphological variation between taxa, there is little variation between chloroplast genomes. The extremely low variation (0.8% informative characters in 6600 bp) in the chloroplast genome makes it unlikely to be useful for reconstructing phylogenies or for assessing molecular homologies. A very fast radiation of the complex, probably during the Pleistocene interglaciations, could explain these results.
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Mauricio Diazgranados\' personal webpage
1 - Saint Louis University, Department of Biology, 3507 Laclede Ave., Macelwane Lab 231, St. Louis, Missouri, 63103-2010, United States of America
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 11:30 AM