Diazgranados, Mauricio .
Testing the conservatism of the ecological niche of the Espeletia complex.
The Espeletia complex (Asteraceae) is a Neotropical monophyletic group of plants of the paramos and high Andean forests of Venezuela, Colombia and Ecuador. The group comprises nearly 137 species, most of them considered keystone species, and unfortunately threatened species too. It has been suggested that the group is a classic example of adaptive radiation in continental “islands”. However, the evolution of the niche is not well known. My goal was to understand if the variation of the niche was positively correlated with the phylogeny of the complex, as a first step to determine if there has been conservatism in the niches along their evolution and radiation. More than 200 herbaria specimens of fourteen species selected from a phylogram for ITS sequences were georeferenced in a GIS with 22 environmental variables. I used the Maximum Entropy Algorithm (Maxent) to model the predicted species geographic distributions. Then I performed pairwise comparisons to identify niche similarities, following two different methods based on the quantification of the probability of occurrence (given by the model) for one species at the collection localities of another species. In addition, I ran Principal Component Analyses with the environmental data for each locality data point to plot the species environmental envelopes and to calculate the percentages of overlapping areas between those. The phylogenetic similarities between species were calculated based on the patristic distances on the phylogram. Finally, Mantel tests were performed to analyze the correlations between the different set of data. The results showed that there is positive correlation between the differences of the ecological niches and the phylogenetic similarities, and therefore the conservatism of the niche was not supported. Consequently, the radiation of the species might have been favored by the rapid adaptation to specific niches, and their future survival would depend on the preservation of them.
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1 - Saint Louis University, Department of Biology, 3507 Laclede Ave., Macelwane Lab 231, St. Louis, Missouri, 63103-2010, United States of America
species distribution models.
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM