About This Project

Mediterranean corals are dramatically affected by mass mortality events linked to marine heat waves. Within species, all individuals are not impacted in the same way: some are more resistant than other to these thermal stresses. Yet, the genomic processes underlying those differential responses are unknown limiting climate-resilient restoration actions. We aim to fill this gap through the production of chromosome level assemblies in 2 species, a prerequisite for population genomics studies.

Ask the Scientists

What is the context of this research?

Warming induced mass mortality events induce strong demographic declines in different Mediterranean habitat-forming octocorals, such as Eunicella singularis and Eunicella cavolini. These events question the species evolutionary trajectory with negative impacts on associated communities. Interestingly, the rates of tissue necrosis and mortality vary among individuals and populations within species, suggesting the occurrence of thermos-resistant individuals. In this framework, we are producing the genomic resources needed to conduct population genomic studies in order to characterize the genomic factors and processes underlying the response to thermal stress. This is a prerequisite to identify warming resistant individuals to be used for warming resilient conservation actions.

What is the significance of this project?

Understanding the processes underlying the response of biodiversity to current warming is a major topic for scientific and manager communities, particularly in the Mediterranean a hotspot of biodiversity and of climate change. Moreover, genomic resources in octocorals are scarce (<10 genomes) but intriguing genomic features had been revealed: variable genome sizes, a mitochondrial gene repair mtMutS and fuzzy species boundaries.

Accordingly, our project is highly significant since the genome assemblies in the two species, Eunicella singularis and Eunicella cavolini, will contribute to 1) improve our understanding in the response of species impacted by warming, with implications for their restoration; 2) support an even distribution of the sequencing effort across the tree of life.

What are the goals of the project?

Our main goal is to improve the quality of existing genome references in the two species, E. cavolini and E. singularis. Thanks to EASI-Genomics support, we generated these genome references using short (Illumina) and long-read (Nanopore) sequencing with annotation from RNAseq. Those small assemblies (446 and 506Mb) show high gene completeness in the two species (88.7 and 90.5%). We now want to increase genome contiguity which are currently 0.5 Mb and 1.9Mb (contig N50). We will conduct Hi-C sequencing on freshly collected samples (two scuba dives for sample collection) targeting the platinium level genome standard. This should allow to characterize the two genomes structure to reach, potentially, a chromosome level assembly.