Species Interactions in Food Webs
Ecological communities can be organized into food webs in which species are inextricably linked within a network of energy flow. Conceivably, all organisms in the network—plants, herbivores, carnivores and detritivores—are functionally predators of resources and resources for predators. From this conception of ecological communities stems a fundamental paradigm for success in the evolutionary-ecological game of life. Namely, individuals ought to strike an adaptive balance between fitness gains from resource consumption and fitness losses from the risk of being consumed. Research in the lab focuses on how this evolutionary adaptive game determines the nature and strength of food web interactions, with cascading effects on community assembly and nutrient cycling through ecosystems.
Food webs, nutrient cycling, and carbon storage in the High Andes
In the essential ecosystem process of nutrient cycling, plants and microbes are generally considered the main biotic players. Plants, of course, take up carbon from the atmosphere and nutrients from the soil, and microbes decompose decaying plant litter and return nutrients and some carbon to the soil. But what happens in ecosystems with little vegetation and almost no plant litter? Julia's research examines how large animals may play an important role in carbon and nutrient cycling in a barren alpine landscape in the High Andes of Argentina. In a system comprised of vicuñas (herbivores), pumas (predators), and condors (scavengers), Julia hypothesizes that carcasses and latrines (communal vicuña scat piles) provide important nutrient inputs into the soil, and that the trophic interactions within this food web determine the distribution and deposition rate of these inputs. She will combine soil sampling and stable isotope analysis at carcasses and latrines to evaluate the effects of puma predation and vicuña anti-predator behavior on the distribution of nutrients in the landscape.
Intraspecific variation and species interactions
A central point of fascination for ecologists and evolutionary biologists alike is the variation across species and between individuals. Yet, models of species interactions in food webs largely ignore variation between individuals and instead assume equal variance by categorizing both individuals and species into broad functional groups. Nathalie embraces the ecological complexity of intraspecific variation by examining the role of animal personality in food web interactions. Animal personality has consequences for the outcome of species interactions and may be an important driver of ecosystem processes. She works primarily with old-field arthropods (Orthoptera and their spider predators) at Yale-Myers Forest and throughout New England.