Phylogenetic Analyses of Andean and Amazonian Tree Communities in Ecuador

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Worthy, Samantha J
Ecuador; DNA barcode; tree; community phylogenetics; Biology
thesis / dissertation description
The forests of Ecuador are known for their high levels of diversity and endemism, classifying the country as a biodiversity hotspot. Both the western Amazon and Andean montane forests are richly populated with tropical tree species that have been little studied in a community phylogenetic context. The implementation of elevational transects and trait based analyses having proven useful in gaining a better understanding ofhow environmental factors are affecting the tree community structure in these habitats. The goal of this research was to evaluate the magnitude ofDNA barcode diversity among Amazonian and Andean tree species. Specifically, the objectives were to (1) evaluate community phylogenetic structure and correlate phylogenetic analyses with diversity metrics among Andean tree species along an elevational gradient at Siempre Verde Reserve, Ecuador, and to (2) construct a tropical tree community phylogeny using DNA barcodes and to test for phylogenetic signal in the occurrence of phytochemicals among tree species within Yasuni National Park, Ecuador. In the montane forest at Siempre Verde, 595 individuals were tagged, collected and identified, comprising 36 families, 53 genera, and 88 species. Analyses revealed that species richness was decreasing with elevation but the number of stems of common species was increasing causing phylogenetic clumping at higher elevations. Evidence implies that habitat filtering of species due to cloud inundation is behind this observed pattern contributing to the community structure. In the upland Amazonian forest of Yasuni, 337 common tree species making up 181 genera and 56 families were sent for sequencing, and the trait distribution of phytochemical presence was determined. Metrics of phylogenetic trait distribution all supported a random distribution of the medicinal trait within the Yasuni tree community. In the future, having higher sequence recovery and resolution along with complete floristic sampling will improve statistical power and the ability to detect fine scale community structure patterns in both of these forests. Studies like this, which include taxonomic, functional, and phylogenetic diversity, will allow for more comparisons to better understand these unique biodiversity hotspots.