OVERVIEW: Identifying and understanding synergies between multiple aspects of global change has been identified as a research and conservation priority. This project aims to address this challenge by exploring the interactive effects of changing climatic context and faunal turnover on a critical ecosystem function – control of infectious disease. Specifically, this study will focus on effects of large wildlife loss (defaunation) and associated replacement with livestock, as this is one of the most prominent forms of faunal change in the Anthropocene. Understanding how such changes in large faunal communities may interact with changing climates to drive changes in risk of tick-borne disease is important and timely. This study will use a large-scale field exclosure experiment, replicated across a strong regional climate gradient that serves as a proxy for regional climate change predictions, to mechanistically examine the effects of large wildlife loss, and the addition of livestock, on tick abundance, prevalence of tick-borne disease, and disease risk, under a range of climatic conditions. This project will be conducted in California, which is experiencing both rapidly warming and drying climates and strong declines in large wildlife with concomitant increases in livestock.
INTELLECTUAL MERIT: While there has been extensive work on the role of climate change in altering parasitism and disease dynamics, much of this research has focused on the direct effects of temperature change on vector or pathogen growth, life history characteristics, and range size. However, changes to climatic conditions will also alter host composition, abundance and behavior, all factors which are likewise independently affected by other forms of anthropogenic disturbance (e.g. defaunation and land use change), which themselves are established drivers of changing landscape scale disease dynamics. It is thus critical to understand how changing climatic context will interact with faunal turnoverin order to move from simple descriptions of current disease dynamics to reliable forecasts of future risk for complex, vector-borne diseases in a rapidly changing world. By utilizing experimental manipulations of wildlife and livestock along strong climate gradients, this study will be able to examine the extent to which these components of global change interact to affect disease dynamics. The large scale (1ha) and long-term (5 year) nature of these manipulations will enable this project to capture the host and vector dynamics most relevant to the transmission of ticks and pathogens.
BROADER IMPACTS: This project will have a strong and diverse set of broader impacts. Results from this research will allow us to identify areas that are most likely to experience increases in disease in a changing climate, and identify how and where changes in large mammal abundance and composition are likely to exacerbate or mediate these differences, thus informing wildlife and livestock management and guiding public health efforts. From an educational perspective, this project will provide critical training for multiple graduate students and undergraduates, with a focus on underrepresented groups. Outreach to grade school children and teachers in training will also amplify the educational value of the project. All data from this project will be made available through open-access publications, and findings will be presented at national and international venues.