Current Research

Testing mechanistic connections between sex, foraging and parasitism along an ecological gradient

Collaborative research with Spencer Hall

Individuals of the same species often differ in important traits, and these differences are known functions of genetic and environmental influences. For most species, however, a mechanistic understanding of the origin and maintenance of individual variation is still missing. This project investigates mechanistic connections among three seemingly unrelated traits: investment in sexual versus asexual reproduction, feeding performance on rich versus poor resources, and susceptibility to parasites. We hypothesize that differences in feeding rates create a causal chain of relationships that ultimately promotes the maintenance of diversity through basic ecological mechanisms. To test these ideas, our research combines monitoring of biodiversity and diseases in natural populations with laboratory experiments designed to disentangle genetic versus environmental factors shaping the traits of individuals. By determining how seemingly unrelated traits are integrated into distinct strategies, and examining how the frequency of different strategies varies along a natural ecological gradient, we are seeking novel insights into the ecological pressures maintaining phenotypic and genetic variation in natural populations.

Community ecology of disease

Collaborative research with Spencer Hall, Meghan Duffy, and Zoi Rapti

As new diseases continue to appear in animal populations, ecologists are increasing faced with answering questions regarding the distribution and prevalence of infection. It some disease systems, it has become clear that species other than the focal host and parasite, such as those that provide food for hosts, compete with hosts for food, and prey on sick hosts, can inhibit or facilitate disease spread. Therefore, interactions with other species may influence the distribution of disease. However, finding mechanistic explanations in this web of direct and indirect effects requires merging aspects of evolutionary biology and epidemiology with community ecology. To make these connections, we have been exploiting an experimentally tractable disease system by using an aquatic parasite (the fungus Metschnikowia bicuspidata) and its host (Daphnia). We build on our own work, as well as that of others, to integrate the role of Daphnia as grazers of algae, competitors with other zooplankton for that algae, and as prey for fishes and invertebrates. Each of these interactions likely influences disease spread among the hosts. For instance, quantity and quality of food resources influence the production of infective forms of the parasite. However, because they consume but do not produce these infective forms, other planktonic competitors may reduce disease. Finally, predators may inhibit disease by eating infected hosts. We approach our system with data-theory integration. We construct mathematical models, refine those models using experiments, and test model predictions with observations of epidemics.

Ecology of stormwater habitats

Collaborative research with Brian Allan, Juma Muturi, Allison Hansen, and Zoi Rapti

Anthropogenic change of the landscape is occurring at unprecedented rates, representing a massive and unplanned ecological experiment affecting both species diversity and the quality of their associated habitats. Typically associated with urbanization is the creation of urban stormwater habitats. These novel habitats, hereafter stormwater ponds, provide us with a unique opportunity to apply ecological and evolutionary theory to better our understanding of the mechanisms underlying the creation and maintenance of biodiversity. Inhabitants of these stormwater ponds include larval mosquitoes, which in their adult life-stage vector a multitude of human disease, posing a large threat to human health. Little is known about the food web structure of these habitats, which limits our ability to predict how ecological interactions may influence disease transmission. To this end, we couple field and laboratory manipulative experiments with mathematical theory to address how ecological interactions in these freshwater ponds influence the abundance and distribution of mosquitoes across the landscape.

Eco-evolutionary feedbacks on community assembly

Collaborative research with Kim Schulz

Understanding the interplay between ecological and evolutionary processes is essential for developing a robust theory of community assembly. We have taken advantage of a unique opportunity to test several tenets of evolving-metacommunity theory in semi-natural pond systems. In 2010, dozens of temporary ponds were constructed in the Heiberg Memorial Forest in New York. Into these new ponds, we manipulate independently both genetic and species diversity of invertebrates immediately after pond construction. We are subsequently measuring priority effects at these different hierarchical levels on genetic diversity, evolution of life history traits, and community assembly patterns.