Diazgranados, Mauricio , Barber, Janet .
Geography shapes the phylogeny of frailejones (Espeletiinae Cuatrec., Asteraceae): a remarkable example of recent rapid radiation in sky islands.
The paramo ecosystem, located above the tree line in the tropical Andes of Colombia, Ecuador and Venezuela, has been the setting for some of the most dramatic recent rapid plant radiations. With an estimated age of 2-4 million years, the paramo is the world's most diverse high-elevation ecosystem. Today more than 140 species of frailejones (subtribe Espeletiinae Cuatrec., Asteraceae) dominate this ecosystem. Frailejones have intrigued naturalists and botanists, not just for their appealing beauty and impressive morphological diversity, but also for their remarkable adaptations to the extremely harsh environmental conditions of the paramo. The subtribe has been classified in eight genera (Carramboa, Coespeletia, Espeletia, Espeletiopsis, Libanothamnus, Paramiflos, Ruilopezia and Tamania). Previous attempts to reconstruct the evolutionary history of this group failed to resolve relationships among genera and species, and there is no agreement regarding the classification of the group. Our goals were to: 1) map the geographic distribution of frailejones to identify patterns of diversity; 2) reconstruct a robust phylogeny using multiple molecular markers; and 3) interpret the phylogeny in a biogeographic context. A geographic information system was built based on 5094 plant collections. Three hotspots of diversity were identified: Merida (in Venezuela), Santander and Boyaca (in Colombia). Phylogenetic analyses were based on multiple markers. Sequence data included nrDNA (ITS and ETS) and cpDNA (rpl16) for a total of 2954 bp. Fragment analysis was performed with AFLP data of 31 primer combinations and 5551 fragments. Phylogenies were reconstructed following MP, ML and BI methods, and a minimum-evolution tree with Nei-Li distance was calculated for AFLP data. Clades for Espeletiopsis, Carramboa and Libanothamnus are recovered, although these genera are not monophyletic and need to be re-defined. Tamania appears nested within Ruilopezia, and Paramiflos within Espeletiopsis. Conflicting positions can be explained by frequent hybridization, hybrid origin and incomplete lineage sorting. Sympatric species tend to be more related to each other than distant species, and there is a strong geographic structure by hotspot of diversity at a regional scale, and by paramo clusters at a local scale. Split-trees reflect this structure and haplotype networks suggest that a few species have played mayor roles in the diversification of the group.
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The Espeletia Project
1 - Saint Louis University & Missouri Botanical Garden, Biology Department, 3507 Laclede Avenue, St. Louis, MO, 63103, United States
2 - Saint Louis University, Biology Department, 3507 Laclede Avenue, St. Louis, MO, 63103, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Franklin A/Hyatt
Date: Tuesday, July 10th, 2012
Time: 10:45 AM