Date of Award

2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Sara Helms Cahan

Abstract

Urbanization is a major feature in modern landscapes. As humans progressively develop land, a patchwork environment appears, with wide variation in the degree of modification. Different animal species can survive in each level of this urban gradient, with populations persisting in disjointed patches of suitable habitat. In this study, I evaluated how urbanization in the Philadelphia Metropolitan Area has affected the population genetics of four ant (Formicidae) species of varying urban aptitude. My focal taxa include Aphaenogaster rudis, a woodland ant which requires forest habitat, Camponotus pennsylvanicus and Crematogaster cerasi, two species which both can inhabit edge habitat and nest in rotting wood, and Nylanderia flavipes, an invasive species known for saturating urban areas. To investigate how each species was impacted, I used microsatellite genotyping with two analysis methodologies: Bayesian population assignment and landscape resistance modeling. Regarding the latter, I tested four hypotheses concerning the relationships between genetic differentiation and landscape characteristics: 1) isolation-by-distance, 2), major geographic barriers, 3) the urbanization gradient, and 4) a habitat suitability gradient. Overall, I found low genetic structure across the four species, but interspecific variation in how landscape characteristics influence genetic differentiation. My results show that genetic response to urbanization in ants varies greatly depending on species and context, with low predictability based on apparent aptitude for the urban environment.

Language

en

Number of Pages

67 p.

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Available for download on Wednesday, December 18, 2024

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