Mississippi State University
Hill, JoVonn G.
Date of Degree
Dissertation - Open Access
Doctor of Philosophy (Ph.D)
College of Arts and Sciences
Department of Biological Sciences
Anthropogenic global change is altering food web dynamics. Global change comprises factors, like temperature, sound, light and more. In this dissertation, I evaluate how two factors, sound and temperature, alter prairie communities. In Chapter 1, I test if sound influences grasshopper respiration rate, thereby altering diet. Some sound frequencies increased grasshopper respiration rate while others decreased respiration rate. Frequencies that elevated respiration rate led to grasshoppers consuming more carbohydrate-rich foods compared to protein-rich foods. This diet change stems from a carbon deficit due to increased respiration rate and could act as a mechanism by which sound pollution indirectly alters plant communities. In Chapter 2, I test the hypothesis that sound can alter grasshopper movement. In response to sound-induced stress grasshoppers may alter their movement in one of two ways: in situ and displacement. I found no evidence that grasshoppers, nor non-Orthopteran insects alter their movement in the presence of sound. This chapter provides foundational methods to evaluate sound for applications in conservation and management. Further research will improve techniques for grassland or agricultural systems. Temperature is another driver of community change. What is less understood is how warming influences predator-pollinator relationships. In Chapter 3, I ask if warming alters a spider that consumes pollinators in a prairie system. My results indicate that pollinators benefit when spiders are not on the flower. Warming shifts spiders down the plant, thus positively impacting pollinator-plant interactions. In addition, warming may benefit plants two-fold if spiders shift their diet to herbivores. This requires additional research, but it is evident that warming generates a positive indirect effect on plants. These chapters contribute to a growing understanding of how global change is restructuring ecosystems. While global change may alter population dynamics or lead to evolutionary change over longer time scales, behavioral responses happen rapidly and can drive ecological dynamics in the short term. My dissertation demonstrates that sound and temperature alter animal behavior that cascades to lower trophic levels. Thus, in addition to demonstrating the indirect effects of global change, these experiments contribute to growing literature on the importance of top-down control in shaping ecosystems.
Wolff, Carter, "Effects of anthropogenic global change on a grassland prairie community" (2022). Theses and Dissertations. 5566.