Phylogenetic Community Assembly of the North American Mixed-Grass Prairie

Phylogenetic Community Assembly of The North American Mixed Grass Prairie Species have evolved in biomes all over the world resulting in biologically diverse communities that gain multiplicity as the distance from the equator decreases. Community ecologists agree there are several factors that shape how communities are populated through time and space. These factors include colonization, speciation, extinction, and evolution which are influenced by environmental filtering and niche conservation (Emerson and Gillespie, 2008). It is hypothesized that many species originated near the equator and radiated to higher latitudes creating a range of species richness known as the latitudinal diversity gradient. Historically ecologists have used species richness, abundance, and functional traits to quantify the biodiversity of an ecological community. With D.P. Faith’s (1992) development of phylogenetic biodiversity measures, which measure the relatedness of organisms based on a comparison of branch lengths on a phylogenetic tree, we are now able to quantify biodiversity on a molecular level. I apply, for the first time, the latitudinal diversity gradient to community assembly of native grassland species. Phylogenetic analysis was used to determine if community assembly is characterized by greater clustering or over-dispersion than expected as distance from the equator increases. The rbcL and matK, chloroplast genes along with ITS1 and ITS2 nuclear DNA regions of over 4500 species were used to infer a phylogeny for North American mixed-grass prairie floral species located in nine remnant prairie communities occurring in three different latitudinal zones. Recommendations for further study are discussed