EAGER: New data for new theory: quantifying resource dynamics inside hosts using emerging techniques to transform our understanding of host-parasite interactions

Parasites are among the most diverse groups of organisms on earth, yet all parasites share the same lifestyle; they steal resources from their hosts to fuel their own growth and reproduction. At present, we cannot accurately predict the growth of parasite populations within hosts because we lack a basic understanding of competition for resources among hosts and parasites. In this project, the researchers will answer fundamental questions about host-parasite resource competition using state of the art analytical chemistry techniques to quantify within-host resources. The answers to these questions will allow researchers to predict the course and outcome of parasite infections and, in the long-term, potentially design innovative new treatments. To maximize the impact of this project on both basic and applied sciences, the researchers will teach other ecologists to use their innovative techniques and introduce ecological concepts to biomedical researchers. This project could change our understanding of how parasites interact with their hosts and could lead to new ways to improve the health of humans, animals and plants. Classical ecological models rarely succeed in providing accurate predictions about parasite population dynamics inside hosts, or parasite’s impact on host fitness, because they fail to capture the resource ecology of the within-host environment. This project will provide proof of concept of a novel approach to studying host-parasite-resource interactions in vivo. The project will employ inductively coupled plasma mass spectrometry, which allows for the simultaneous quantification of multiple elements, in a flagship model system of host-parasite resource competition (Daphnia-Pasteuria). The researchers will quantify (1) the in vivo resource requirements of parasites across their life cycle and (2) the spatiotemporal dynamics of resources at the scales (i.e. tissue and whole-host) that determine parasite and host fitness, over the course of infection. The project will provide the missing data needed to build quantitative, predictive models of parasite population dynamics and host-parasite resource competition in this study system. Furthermore, it will provide a new toolkit for the study of within-host dynamics in other host-parasite systems. Together, these aims will provide the means to build and test a general theory of within-host resource competition. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.