Biotic and abiotic drivers of pathogen prevalence in a rust fungus with multiple plant hosts

Abstract

Pathogens can have strong negative effects on individual fitness that scale up to influence population dynamics. Because of this, understanding the ecological contexts that shape pathogen transmission and prevalence is critical for understanding community dynamics and ecosystem function. Puccinia monoica is a fungal pathogen with a complex life cycle that alternates between infecting grasses and forbs in the Brassicaceae. This study investigates how B. stricta and grass host densities, as well as abiotic factors such as drought, influence transmission of P. monoica. I conducted field surveys near Gothic, Colorado, to quantify environmental conditions across multiple sites with variation in host and pathogen abundance. Furthermore, to experimentally test the potential role of drought in facilitating pathogen spread, I performed controlled inoculations of grass hosts under drought and control conditions in a greenhouse. These integrated field and experimental approaches helped reveal how spatial variation in biotic and abiotic environments shape pathogen dynamics in multispecies communities. By quantifying relationships between host density, environmental stress, and pathogen transmission, this study supports our understanding of the population ecology of plant-pathogen systems which could inform models of disease spread under changing climate conditions.