Large infectious disease outbreaks allow for relatively faster evolutionary changes in the host, the infectious pathogen, and the community of microorganisms living within the host (the microbiome). While these interactions are poorly understood, they're extremely important in predicting and controlling future outbreaks. The largest recorded marine epidemic ever recorded is currently ongoing in intertidal ecosystems along the west coast of North America. Sea star wasting disease (SSWD) is effecting sea star populations from South Eastern Alaska to Baja California, Mexico and local extinctions are a serious concern. Large-scale epidemics such as these are expected to become more common as the global environment and species' population distributions change. This current disease event provides a unique opportunity to better understand how hosts, the hosts' microbiome, and the disease causing pathogen change throughout an epidemic. The research proposed here will lead to a deeper understanding of these disease events from an evolutionary and ecological perspective by characterizing changes in host and pathogen due to natural selection following epidemics.
This project aims to understand the impact of the microbiome and virome on host disease status and progression at the individual, population, and community levels. The work will contribute to the understanding of an organism as a sum of its inhabitants and will dissect the role of the microbial community in physiological and evolutionary responses to disease. Disease may often be due to a disruption in the balance of an organisms' complex community of microorganisms. Thus, the evolution of disease is not the coevolution of two players (host and pathogen), but rather the coevolution of all members of the host's community. The ongoing Sea Star Wasting Disease event provides a unique opportunity to investigate how this evolution plays out in a widespread epidemic. Specifically, the proposed research aims to (1) identify the targets of natural selection in host and virus populations and (2) investigate molecular mechanisms in the host, virus, and microbiome that underline resistance in hosts and virulence in virus in order to identify the tipping point between asymptomatic and symptomatic hosts. This will be accomplished using a novel sequencing technique that simultaneously collects sequence data from the transcripts of the eukaryotic host, bacterial community, and viral community. This approach allows for identification of the major players in the interaction as well as their functional roles. The understanding of this complicated coevolution will impact the fields of disease ecology and evolution as well as affect the way wildlife and human diseases are understood and, hopefully, prevented or controlled.
