Beasley, DeAnna E.
University of Tennessee at Chattanooga
Place of Publication
There are two aims to this study: compare diversity across an urban gradient and across seasons. We deployed traps and identified the collected 12 ant species at nine different sites centered at Chattanooga, Tennessee, for the purpose of relating levels of urbanization to the diversity of ant species at each site. We successfully sampled in the summer (June 27, 2017) and spring (March 31, 2018), and unsuccessfully sampled in winter (Feb. 16, 2018) when we collected zero ants, likely due to cold soil temperatures. To quantify “urbanization” we divided the sites into “Urban” core verses surrounding “Suburban” area using a city development model, and by a direct measure of the percent impervious surface within a 25m radius of each collection site. We predict that as urbanization increases, ant diversity will decrease. We found that the “Suburban” versus “Urban” sites showed a decline in species diversity for the summer sampling (averages of 4.6 and 2.2, respectively), but no difference for the Spring sampling (averages of 2.0 and 2.0). Impervious surface percentage was strongly related (r2 = 0.63) to a decline in ant species over the combined summer and spring samplings. Our linear least-squares regression line slope indicates a decline of 0.34 species for every 10% increase in impervious surface area, with a modeled 6.4 species for pavement-free land cover and 2.9 species for 100% impervious surface. Overall, our ant samplings support this hypothesis for our measures of urbanization. Characteristics of urbanization include impervious surface coverage, fragmentation of habitats, warmer micro-climates, and human food wastes. In general, it is believed that urbanization favors the “opportunistic” or “generalistic” ant species that can thrive on a variety of food and water sources in dense human populations. These species displace the more numerous “specialist” species, resulting in less ant diversity with increasing levels of urbanization.
I would like to extend my thanks to Dr. Beasley for her guidance and encouragement to see this project to completion. I thank Dr. Stylianos for his support for this project. I would also like to thank Itzel Guzman Hernandez and Hannah Hightower for their help in the field and laboratory. I thank the city of Chattanooga for permission to sample for this study. Finally, I would like to thank the Brock Scholar Program for promoting this type of undergraduate research opportunities.
B. S.; An honors thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Bachelor of Science.
Ants; Urban pests
Brooks, Hao, "Changes in ant biodiversity across an urban gradient" (2018). Honors Theses.