Specialization and trade-offs in plant-feeding insects

SPECIALIZATION AND TRADE-OFFS IN PLANT-FEEDING INSECTS SEPTEMBER 2017 DANIEL A. PETERSON, B.A., AMHERST COLLEGE M.S., UNIVERSITY OF WASHINGTON Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Benjamin B. Normark The immense diversity of life on Earth has been attributed to the partitioning of available resources into ecological niches, but it is not obvious what determines the niche size of each species. For example, most plant-feeding insects consume only one or a few closely-related host-plant species despite the advantages of having a broader diet. Many researchers have therefore suggested that the evolution of broad diets in plant-feeding insects must be constrained by genetic trade-offs between adaptations to alternative hostplants. Despite its intuitive feel, however, little empirical evidence in support of the tradeoff hypothesis has emerged from decades of experimental studies comparing individual performance on alternative hosts within insect populations. Here I use a broader approach to evaluate the role of trade-offs in driving ecological specialization in plant-feeding insects. By collecting host-use data for thousands of insect species and fitting those data into long-term evolutionary models, I investigate whether trade-off constraints have left observable signatures in the present ecological niches of existing species. Chapter 1 focuses on a single family of insects, the