Postdoctoral Fellowship: OCE-PRF: A holobiont approach to rapid thermal evolution using an emerging copepod model system

How an organism responds to environmental stress has been a central question in evolutionary biology since its inception, but climate change has turned this interest into an imperative. Prior research has focused on individual species’ response mechanisms from the perspective of adaptation and acclimation, but there is a recent appreciation for how species interactions are also central to climate resilience.

An organism’s interactions with its microbiome are one of these interactions, which have been recently identified as a key component of thermal resistance. We know very little about the microbiome of the most abundant animal on the planet, copepods, which may present an important yet unexplored component of their evolutionary and ecological dynamics under climate change.

Copepods are experiencing massive die-offs due to increasing ocean temperatures, placing marine food webs and commercially-important fish stocks, such as cod, at risk. How the copepod microbiome changes and perhaps even mediates responses to thermal stress is unknown and precisely what the proposed project will ascertain. The proposed research will generate foundational data on the copepod microbiome and its link to thermal resilience.

The insights gained will provide an additional diagnostic tool for assessing the impacts that coastal communities and fisheries may face under climate change. Furthermore, the project will generate opportunities for historically-excluded undergraduate students to participate in research, and develop an art-science communication module for the University of Vermont's Department of Biology.

These initiatives will broaden the scope of participation within STEM and equip the next generation with new tools for sharing their science and engaging the larger community in the protection of marine ecosystems.

This project explores how thermal evolutionary trajectories are shaped by the microbiome in the emerging model system, the copepod Acartia tonsa. The study will sample A. tonsa from its southernmost population in North America, Key Largo, Florida, and experimentally evolve these organisms at an elevated temperature with and without a probiotic treatment.

The project PI has chosen this particular population, as it experiences a monthly mean temperature of 25C, as compared to more northern sites experiencing temperatures closer to 18C, thus yielding interesting insights on thermal adaptation. This project has three main objectives: 1) Determine the microbial composition of A. tonsa’s North American southernmost population and its variation across generations experiencing elevated temperatures and/or probiotics, 2) Assess the fitness consequences of A. tonsa experiencing elevated temperatures and determine if adding a previously identified putatively beneficial bacteria can rescue observed fitness costs, and 3) Link the functional potential of A. tonsa’s microbiome to the functions of the host’s loci under selection to determine if there is a synergy between host and microbiome response pathways.

This project provides an unparalleled opportunity to consider how the host and its microbiome in tandem may shape or even offset each other’s responses to thermal stress, providing key understanding into the multiple factors involved in thermal resilience that will bolster marine ecosystem management.

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.