Professor Meghan Duffy is part of a National Science Foundation grant of just under $925,000 for the collaborative research project “Friendly competition - infusing ecology and evolution at the frontiers of the dilution effect in disease ecology.”

Duffy was awarded close to $225,000 of the total grant. She’s working with collaborator and lead principle investigator Dr. Spencer Hall, Indiana University and other principal investigators Drs. Carla Cáceres and Zoi Rapti, University of Illinois. The three-year grant began June 1, 2014.

According to the project summary, outbreaks of disease continue to increase in wild populations, and understanding this increase has become a major environmental challenge. A popular explanation is that loss of biodiversity, and particularly of species that are resistant to disease, encourages disease epidemics. Thus, enhancement and preservation of species diversity might reduce disease and associated negative effects on host populations.

This project combines new mathematical models with experiments to challenge this explanation in a food web/community context, using Daphnia (an aquatic invertebrate) and a fungal pathogen. They will explore how the dilution effect of multiple pathogen hosts plays itself out in the face of ecological (interspecific competition) and evolutionary dynamics. The researchers propose that key traits determining transmission also affect interactions with other community members, exploitative competitors and their shared prey in this case, which may alter the details of host-pathogen dynamics, particularly the dilution effect. Models and experiments together will determine whether competition among hosts also influences the spread of disease, whether nutritional value of the food for which hosts compete influences susceptibility to disease, and whether rapid adaptation of hosts to disease can counteract the loss of biodiversity, potentially reducing disease outbreaks.

An interdisciplinary team of researchers will tackle these issues using common freshwater organisms that are infected by a virulent pathogen. The Daphnia-fungus system is ideal for asking elegant theoretical questions, and the proposed ambitious experiments will generate empirical data to test the theory. This multi-disciplinary project will produce new insights into a provocative option for disease control.

“The dilution effect is the idea that adding biodiversity reduces disease if the hosts added are less susceptible than the focal host,” said Duffy. “This suggests that maintaining biodiversity might be important for protecting focal host populations. However, our project will add in another wrinkle: that those additional species are also likely to compete for the same food resources as the focal species. What is the net outcome of these positive and negative effects of biodiversity? Can we predict the effects of changing diversity?”