The Evolution of Fear Ecology: A Fruit Fly (Drosophila melanogaster) Perspective

Several mechanisms underlie how evolutionary lineages respond to predation pressures or predation risk. Further mechanisms link evolutionary predation responses to how animals forage, or find mates. However, gaps remain in our understanding about how predation and foraging interact in an evolutionary context. In my first chapter, I elaborate on how predation and foraging relate in to one another in ecological, evolutionary and behavioral contexts. I start out with an overview of fear ecology. Then, I outline how trade-offs influence the evolution of morphological, chemical and behavioral responses to predation. I further elaborate on how these trade-offs influence reproduction. Finally, I go into detail on how the fruit fly, Drosophila melanogaster, has been used to study predation and foraging, and how it can also be used to study the gaps in our knowledge of the mechanisms behind evolutionary responses to predation in a foraging context. In the second chapter, I delve into innate bias and how it can aid a forager when choosing between patches. Innate bias can be influenced by several factors such as spatial scale and the decoy effect. Additionally, innate bias sometimes cannot be generalized across contexts. I do this in the context of a large scale patch study with experimentally evolved lines of Drosophila melanogaster. These lines have been selected for an innate preference for laying eggs on either an orange or pineapple substrate. Finally, in my third chapter, I explore how predation can influence the decisions of the same innate preference lines of flies. I do this in a study where I give the flies a choice of laying eggs on a safe patch without predators and one with a live Chinese mantid (Tenodera sinensis). Additionally, these patches reflected the innate preference of the line being tested. Here I looked at how the fly might take more risks to go to a preferred patch or change their patch preference in the presence of a predator