Zapata, Felipe .
Diversification in the mountains of South America: Phylogenetics and species limits in Escallonia (Escalloniaceae).
Detailed knowledge of the evolutionary history and the species boundaries of organisms occurring in hotspots of biodiversity may provide valuable insights for unravelling the patterns and process underpinning biodiversity. Escallonia (Escalloniaceae), a morphologically and ecologically diverse genus with 39 species found throughout the Andes and the highlands of southeastern Brazil, provides an ideal opportunity to study the diversification of a group of woody plants from the biodiverse mountains of South America. Based on a comprehensive taxonomic and geographic sampling (35 species), I analyzed patterns of variation in molecular (3 unlinked markers; 100 accessions), phenotypic (40 characters; 680 specimens) and bioclimatic (19 variables; 680 unique localities) variables to reconstruct the evolutionary history of Escallonia and evaluate species boundaries within this genus. Molecular phylogenetic analyses revealed i) that Escallonia is monophyletic, ii) a remarkable level of geographical phylogenetic structure, and iii) a widespread absence of species-level monophyly (22 species). These results are consistent with the hypothesis that geography played an important role early in the history of Escallonia by separating populations, which later diversified rapidly and/or recently in isolation. Morpho-geographic multivariate analyses showed evidence for morphological discontinuities supporting seven hypothesized species boundaries, suggesting that in this group neutral molecular variation and phenotypic variation may not be evolving in concert. Multivariate analyses of bioclimatic variables indicated that 12 hypothesized species differed in their bioclimatic niche, suggesting that these species, some sympatric, display differences in their present day selective regimes. Interpreting these three operational species criteria in the light of the General Lineage Species Concept (GLSC) suggests that most species (71%) within Escallonia represent distinct evolutionary lineages on independent evolutionary trajectories. Taken together, these results illustrate a powerful mutidimensional approach to studying the diversification of a plant clade, emphasizing the collection and integration of a variety of biological data to illuminate our understanding on the origin and evolution of plant species.
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1 - University Of California, Department Of Integrative Biology, 3060 Valley Life Sciences Bldg. #3140, Berkeley, CA, 94720-3140, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lindell A/Chase Park Plaza
Date: Tuesday, July 12th, 2011
Time: 10:45 AM