Date of Award

12-2015

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

Joseph K. Bailey

Committee Members

Jennifer A. Schweitzer, Charles Kwit

Abstract

Urbanization is rapidly increasing as human population growth steadily grows, but there is little consensus of the ecological consequence of this population shift and almost no information of the evolutionary consequences for local biodiversity. Nearly two-thirds of the world’s population will live in city centers by 2050 with profound impacts on landscapes that can act as important agents of selection. This study aims to identify 1) the net effect of urbanization on species richness, 2) how phylogenetic diversity varies between urban and rural sites, and 3) the strength of urbanization as a selection pressure. First, a meta-analysis was conducted in order to calculate an overall effect size that reflects differences in species richness in urban versus rural sites. Then a subset of the data was used to calculate phylogenetic species variance (PSV), phylogenetic species richness (PSR), and species richness (SR) of plants within urban and rural sites. Lastly, a SURFACE analysis, using a combined phylogeny of the species surveyed, was used to detect regime shifts and quantify the strength of selection. These results show: 1) species richness is significantly lower in urban ecosystems than and rural; 2) no difference in PSV, PSR, and SR between urban and rural ecosystems; but 3) there was a strong phylogenetic signal for plant responses to urbanization. The results of this study indicate that urbanization is selecting novel communities based on highly conserved functional traits. As global populations continue to grow, urbanization will continue to be a strong force of natural selection and urban centers may become a new evolutionary landscape with novel conservation strategies required to preserve associated biodiversity.

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