Project: OCE-PRF: Drivers of phenotypic diversity and adaptation in asexually propagating coral populations

NSF Award Abstract:
This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

In this era of rapid environmental change and degradation, the survival of marine organisms will depend largely upon their ability to tolerate increasing environmental stress. However, the processes that drive resilience (e.g., the relative contribution of genetic versus environmental factors) remain largely a mystery. Corals are a major focus of current studies on organismal resilience because they are undergoing a worldwide decline, and they are so important for both the health of the oceans and the welfare of coastal communities. Corals often occupy and build habitats through asexual reproduction (production of clones), and it is widely assumed that such asexual populations may lack sufficient genetic diversity to respond to diverse environmental stressors. However, few previous studies have quantified the effects of asexual reproduction on the ability of corals to respond to environmental change. This research explores the different mechanisms that contribute to differences in coral stress response among two predominately clonal populations of the Caribbean thin finger coral (Porites divaricata) dwelling in distinct habitat types (mangroves vs. reef). This research will illuminate the drivers of organismal resilience, potentially impacting ongoing coral conservation and restoration efforts. It will also broaden the participation of underrepresented groups by encouraging active participation by local community members, students and scientists at the University of Belize, as well as providing unique training opportunities for next-generation scientists at the interface of field marine ecology and genomics. Importantly, these results will be communicated to a wide audience through diverse venues, including technical reports and management recommendations provided for government agencies and non-profit Belizean conservation organizations, popular articles and curricular materials for the community at large, and peer-reviewed manuscripts and presentations targeted to the scientific community.

Among conservation biologists and ecologists, there is an urgent effort underway to understand the causes of diversity in traits impacting organismal survival and reproduction. If we are to understand how natural populations will respond to environmental change, it is critical to understand how genetic, epigenetic, and environmental factors impact resilience. Such studies have advanced significantly in many plant species, but they are only just beginning to be applied to animals like corals. As in many plants, the model species used here - Caribbean thin finger coral (Porites divaricata) - reproduces primarily asexually, allowing us to compare the performance of clones in different environments and isolate the effects of genotype, epigenetics (namely DNA methylation), environment, and somatic mutations on variation in stress-related coral traits. Specially, combining fully-crossed reciprocally transplanted coral ramets across mangrove and reef sites with genomic and methylation sequencing data, this research will evaluate 1) the role of intra-genet variation accumulated during asexual reproduction in facilitating adaptation in the mangrove population, relative to roles of between-genet variation and phenotypic plasticity, 2) assess the role of new DNA methylation states, and 3) measure the rate of accumulation of new DNA methylation marks and base-changes during asexual reproduction. Results from this research effort will advance our understanding of the role of mechanisms like DNA methylation and somatic mutations in driving phenotypic variation in critical stress-response traits and how these mutations accumulate over time, provide insight into how such mechanisms are generated and inherited across asexual generations, build upon the sparse understanding of the role of novel habitat types, i.e. mangroves, in coral ecology and evolution; and generate novel molecular resources including the first reference genome assembly for the non-model coral, P. divaricata.

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.