Unravelling the holobiont diversity in a temperate octocoral over contrasting environments
Abstract
The holobiont concept is central in the understanding of how organisms, especially corals, adapt to different environment It integrates the evolution of an organism alongside its symbiotic microbial associates. Here, we studied the diversity of bacterial communities associated with the Mediterranean octocoral Eunicella cavolini, in sites with contrasting ecologies at two different seasons. This comparison included coastal sites located near pollution sources, and offshore sites, potentially less impacted. The analysis took into account the genomic diversity of the host, estimated using Restriction Site Associated DNA (RAD) sequencing. We evidenced variations in the gorgonian microbiome over short distances, primarily between offshore and coastal sites (8 km distance), and less variation between seasons. Differences in bacterial communities among colonies included changes in the relative abundance of Endozoicomonas, the dominant bacteria associated with E. cavolini. Differences in the microbiome were also observed in the composition of Endozoicomonas amplicon sequence variants (ASVs) between colonies and sites. Conversely, the gorgonian displayed very low genetic structure among sites, with some outlier loci uncorrelated with the local environment. We detected a significant correlation between Endozoicomonas ASV counts and RAD host genotypes, which could indicate a direct effect of the host genotype on bacterial strains, or an indirect effect of local ecological conditions on both host and bacteria. These results highlight the importance to consider the diversity of different holobiont compartments when studying adaptation to local environments.
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BibTeX
@misc{bally2026unravelling,
title = {{Unravelling the holobiont diversity in a temperate octocoral over contrasting environments}},
author = {Marc Bally and Dorian Guillemain and Sandrine Chenesseau and Jean-Baptiste Ledoux and Stephane Sartoretto and Sarah Samadi and D. Aurelle},
howpublished = {HAL},
year = {2026},
month = sep,
url = {https://hal.science/hal-05728502v2},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Unravelling the holobiont diversity in a temperate octocoral over contrasting environments
AU - Marc Bally
AU - Dorian Guillemain
AU - Sandrine Chenesseau
AU - Jean-Baptiste Ledoux
AU - Stephane Sartoretto
AU - Sarah Samadi
AU - D. Aurelle
PY - 2026
DA - 2026/09/02
PB - HAL
UR - https://hal.science/hal-05728502v2
AB - The holobiont concept is central in the understanding of how organisms, especially corals, adapt to different environment It integrates the evolution of an organism alongside its symbiotic microbial associates. Here, we studied the diversity of bacterial communities associated with the Mediterranean octocoral Eunicella cavolini, in sites with contrasting ecologies at two different seasons. This comparison included coastal sites located near pollution sources, and offshore sites, potentially less impacted. The analysis took into account the genomic diversity of the host, estimated using Restriction Site Associated DNA (RAD) sequencing. We evidenced variations in the gorgonian microbiome over short distances, primarily between offshore and coastal sites (8 km distance), and less variation between seasons. Differences in bacterial communities among colonies included changes in the relative abundance of Endozoicomonas, the dominant bacteria associated with E. cavolini. Differences in the microbiome were also observed in the composition of Endozoicomonas amplicon sequence variants (ASVs) between colonies and sites. Conversely, the gorgonian displayed very low genetic structure among sites, with some outlier loci uncorrelated with the local environment. We detected a significant correlation between Endozoicomonas ASV counts and RAD host genotypes, which could indicate a direct effect of the host genotype on bacterial strains, or an indirect effect of local ecological conditions on both host and bacteria. These results highlight the importance to consider the diversity of different holobiont compartments when studying adaptation to local environments.
ER -