Native Ant Biodiversity Response to A Dominant Competitor in Pine-Hardwood Forests of Alabama, USA

Abstract

This thesis explores how invasive species affect native biodiversity. Specifically, I explore how the invasive ant species, Solenopsis invicta influences the recipient native ant community in pine-hardwood forests. These habitats were chosen as there is current debate on whether the invasive S. invictacan persist in habitats with little disturbance and whether theeffects of S. invicta on the ant community are similar to the effects in more disturbed habitats. I first explore the relationship between S. invicta and native ant biodiversity metrics at ten pine-hardwood forests in chapter one. The results of which indicate no observable effects of S. invictaon any of the native ant biodiversity metrics included in analysis. Furthermore, results from a co-occurrence and path analysis suggest that 1) S. invicta is not responsible for any negative occurrence pairings with any ant species present at the sites and that 2) variables associated with habitat fragmentation and disturbance (site county human population size) have a greater impact on native ant diversity. The second chapter explores the direct effect of S. invicta on native ant species through an experimental removal study that took place in the summer of 2021. Upon removal of S. invicta, I found that treatment plots had significantly fewer S. invicta workers present, as well as decreased native ant abundance relative to the control plots. These results suggest that removal of S. invicta does not have positive effects on the present native ant community and that native ant species may have adapted to the presence of S. invictaworkers as indicated by decreased native ant abundance in treatment plots. The results of the work shed light on the interactions between native and invasive species as well as how factors associated with habitat disturbance (presence of invasive species, increased human presence) affect native ant diversity.