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theses

The creation and expansion of cities and suburban developments impact the ability of plant species to survive and reproduce on local, regional, and global scales. With over 50% of the world’s growing human population residing in urban areas, the identification and qualification of plants found in such regions is becoming increasingly important to both understand the urban-nature biological interface and counteract the “extinction of experience” of nature for city dwellers. My dissertation project uses field surveys of urban plant communities in disturbed habitats, an international plant trait database, common garden experiments of populations of a native, weedy herb, Plantago rugelii (American or blackseed plantain, in the family Plantaginaceae), and a newly developed public science education and outreach activity focused on edible urban weeds. My overarching questions were, (1) How do community and population-level traits differ between vascular plants of urban and exurban environments; (2) How do native plant populations evolve in response to urbanization; and (3) How do these community shifts and evolutionary outcomes for urban flora redefine the scope of urban botanical education? I used Bayesian statistical inference to answer questions about trait patterns and upheld expectations for higher standards of hypothesis testing in the plant sciences. My main research findings were that (1) the flora of asphalted parking lots have reduced beta diversity, reduced phylogenetic diversity, and larger proportions of short-lived, non-woody, and C4 plant species compared to the surrounding regional species pool; (2) parking lots filter for plant species with combined abiotic and biotic pollination strategies and generalized dispersal strategies involving animal vectors from across multiple taxonomic orders; and (3) urban P. rugelii have fewer reproductive spikes, longer time to maturation of fruit, taller maximum spike height, and reduced leaf thickness compared to rural populations of the same species across the Philadelphia and New York City Metropolitan Areas. My botanical education activity details a successful outreach event and provides public access to learning and teaching materials for utilizing six, locally-abundant, and spontaneous urban plant species in urban environmental education. My results show evidence of community-level functional trait filtering in urban hardscape habitats driven by deterministic, niche-based assembly rules; urban phenotypic divergence and evolution of spontaneous species via natural selection; and the ability of commonly overlooked yet freely available urban weeds to inspire and inform learners of all ages. I have also established parking lots and a common, widespread native species as models for analyzing urbanization at a local scale but in the context of global environmental change. Weedy plant species are ideal models for studies of global urban evolution as well as for use in urban environmental education. Increasing the extent and understanding of spontaneously vegetated areas will ultimately lead to reciprocal benefits for humans and nature.

ETD_9901

Ph.D.

Includes bibliographical references

doi:10.7282/t3-1wgq-7x53

ETD doctoral

The author owns the copyright to this work.