CAREER: Understanding the mechanisms that mediate the effects of local ecology on geographic mosaics of host-parasite interactions

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Environmental temperatures can influence host-parasite relationships by affecting the effectiveness of host defenses and parasite survival. Experimentally elevated temperatures can favor the host’s immune response but can be at the upper thermal limits for which parasites survive and exploit the host. Temperatures can alternatively induce heat stress for hosts, reducing their capacity to resist parasites. This paradox suggests that the effect of temperature deviations on host-parasite interactions might be related to local adaptation to climate, which could explain geographical variation in the hosts’ immune response. The goal of this research is to use coordinated, experimental approaches to determine how environmental factors affect interactions between nest parasites and their box-nesting host, eastern bluebirds (Sialia sialis) across the eastern US. First, the research will examine the relationship among local environmental factors, nest parasite factors, and host nesting success with publicly available environmental data, as well as host and parasite data collected through a recently established, citizen science project: “Nest Parasite Community Science Project”. Next, the research will use coordinated experiments to determine how temperature affects host immune development and parasite survival across the bluebird’s range. The research will build lasting connections with K-12 teachers at underserved magnet schools and the public from the Nest Parasite Community Science Project through learning and being involved in the entire process of a scientific study. Not only can a relationship with nature promote mental health, but community-based science projects can help educate the public on environmental issues so that they make informed decisions in society.The proposed research examines host-parasite geographic mosaics by using coordinated, experimental approaches to determine how environmental factors affect host-parasite interactions across an environmental gradient. The central hypothesis is that variation in temperature is an important driver of host-parasite mosaics, and the outcome of which is mediated by the differential effects of temperature on parasite fitness and early-life host immunological resistance across the host range. The research will test this hypothesis by spatially and temporally modeling local environmental factors, presence and abundance of nest parasite taxa, and host nesting success across the host’s range. The research will also determine whether experimental changes in temperature during the different stages of development influences outcomes of early-life immunity against parasites. Specifically, temperature (hotter, colder, no change) will be manipulated at different host developmental stages, before and while host and parasites are interacting, and changes in immune mechanisms and nest parasite factors will be characterized. Coordinated efforts across multiple scales are critically needed to causally determine the underlying mechanisms that create and maintain host-parasite geographic mosaics across an environmental gradient. To be in multiple places at the same time requires collaborations with research scientists or community-based scientists across a multitude of locations. By creatively linking the general public, professors, and K-12, undergraduate, and graduate students, the proposed research promises to provide novel insights into the emerging field of eco-evo dynamics through transforming our understanding of the causal environmental factors and mechanisms that facilitate host-parasite geographic mosaics.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.