Research

Food Web Ecology

The scope of my research program is understanding terrestrial invertebrate food webs, with a particular emphasis on the role omnivores play in their communities. Incorporating omnivory into our knowledge of food web dynamics is a fascinating challenge with many unresolved questions. These include: how do omnivores affect the population dynamics of their prey, competitors, and predators? How heavily do different omnivores rely on different resources? How should trophic level models calculate the trophic position of omnivores to accurately reflect their food web position? I address these questions with a combination of manipulative and observational field study, laboratory mesocosm experiments, and stable isotopic analysis. 

Stable Isotopes in Ecology

The application of stable isotope techniques to ecological questions has opened a new frontier in our understanding of animal diet, animal movement and migratory patterns, food web structure, and ecophysiology. Stable isotope analysis takes advantage of naturally-occurring differences in the ratios of heavy to light isotopes in biologically relevant elements, such as carbon and nitrogen. Recent research suggests that initial assumptions about the behavior of stable isotopes in arthropods may not be universal. Much work is needed to develop reliable models of enrichment for many important terrestrial invertebrate groups. Read more about stable isotopes in ecological investigation here.

Invasion Biology

During my postdoctoral research in the laboratory of Andrew Suarez at UIUC, I have been working with the invasive Argentine ant, Linepithema humile, in both native and introduced ranges. With collaborators David Holway and Ed LeBrun (UC-San Diego) we are studying the competitive interactions among Argentine ants and other ant species in their native range, including the fire ant, Solenopsis invicta. In addition to field behavioral experiments, we collected hundreds of ant and other arthropod specimens for stable isotopic analysis, allowing us to characterize for the first time the trophic ecology of the ants in these communities that have given the world two of the most pernicious invasive species. 

Ant-Plant Symbioses

Aside from a few well-known ant-plant systems, a vast diversity of ant-plant interactions exist that have yet to be explored in detail. My dissertation research focused on the relationship between the neotropical ant plant Cordia alliodora and its ant inhabitants. I discovered that different ant species exhibited varying levels of protective behaviors, ranging from mutualism to parasitism. In addition to more vigorous protective behaviors, the mutualistic ants had evidence of incorporation of insect prey from the plant’s surface, while the parasitic species appeared to rely more heavily on tending phloem-feeding scale insects.  I also investigated habitat partitioning of the tree’s domatia among the different inhabiting ant species.  I discovered that the more aggressive mutualistic species tend to exclude each other from the same tree, while the more timid parasitic species co-occurred in trees with the aggressive species.