The mass coral bleaching event currently occurring in French Polynesia offers an opportunity to test hypotheses regarding mechanisms of rapid response to large scale disturbances. Colonies of Acropora hyacinthus, a widespread major reef-building coral in the Indo-Pacific, showed variable bleaching severity and prevalence in the field (April 2019), and we propose to investigate potential epigenetic and genetic mechanisms involved in either resisting stress or recovering from bleaching. This project will leverage the Moorea Coral Reef (MCR) LTER, which will allow us to integrate high resolution oceanographic metrics and data on long-term community dynamics into our study on rapid adaptation of Acropora hyacinthus. We propose to track genetic and epigenetic signatures of a natural selection event (bleaching) in the field and test the impact of bleaching history on reproductive and carry-over effects in larval and juvenile corals. This work will investigate associations between selection on genetic variation and epigenetic variation as well as the potential role of DNA methylation in phenotypic change across a generation in association with coral bleaching. In this era of global change, mounting evidence is showing that rapid evolutionary processes are occurring at time scales relevant to ecological processes. Therefore, capitalizing on a system with rich long-term ecological data, such as that associated with the MCR LTER, is ideal to investigate mechanisms of rapid adaptation.
This research will provide valuable resolution on how coral reefs recover from repeated, and variable, disturbance regimes. To date, there is limited data on reproductive biology of major reef-building corals in the MCR, therefore data generated through the proposed research will give valuable insight into potential mechanisms of resiliency of coral reef ecosystems. Further, there is a gap of knowledge on how allele frequency shifts are occurring across ecological time scales associated with the LTER, especially in response to strong selection events, and this proposed project would begin to address this gap. This also provides an opportunity to investigate interactions between allele frequency shifts and changes in epigenetic processes, which could drive rapid adaptation in the face of disturbances. Finally, by focusing on sites around the island with variable recovery dynamics, we can gain a broader picture of coral community resiliency in a relatively healthy ecosystem. Taken together, this proposed research in association with the MCR LTER could elucidate critical mechanisms of long-term response in coral populations that could be expanded globally.
Data from this project will be come of the first of its kind ? namely, linking changes on the DNA methylome to the response to bleaching in the field context. In addition, the insight gained as a result of this proposed work will likely contribute to the management of coral reefs, providing information about how the interaction of 3 processes - previous experience of the coral, genetics and epigenetics ? might intersect to influence resistance to and resilience from a bleaching event. Importantly, this work will fill an important knowledge gap about mechanisms by which bleaching events shape future coral populations. In addition to contributions to research, this collaborative project will support four early career researchers (junior faculty and graduate students), many of them female or from underrepresented groups. Further, the proposed research has ample opportunities for undergraduate research projects and we intend to heavily involve undergraduates at Auburn University for data processing and analysis. We aim to involve 3 senior graduate students and >5 undergraduate students in various aspects of the proposed projects. In addition, if supported, this project would benefit early career researchers at an EPSCoR institution.