Levitan, D. R. | Search bioRxiv

bioRxiv2026

Genetic diversity of endangered Acropora spp. corals in Bonaire: implications for restoration and gene banking

Species restoration is a valuable tool to combat biodiversity loss. However, maintaining genetic diversity in species restoration is challenging, particularly for species that can reproduce asexually, such as plants and corals, because a seemingly diverse collection of individuals could be composed of many clones of a few genotypes. Caribbean elkhorn and staghorn corals (Acropora palmata, A. cervicornis) are critically endangered reef-building corals that are a major target for restoration. To better understand the genetic diversity of an Acropora spp. restoration program and interpret local population genetic structure, we conducted microsatellite genotyping on the gene banks of 35 A. palmata lineages and 25 A. cervicornis lineages maintained by Reef Renewal Foundation Bonaire (RRFB) in the Caribbean Netherlands. We found that RRFB had high genotypic richness for A. palmata (0.971) and A. cervicornis (1.0) and estimated that they captured 88.9% and 74.7% of Bonaires microsatellite asymptotic allelic diversity, respectively. Compared to populations of Acropora spp. studied in other locations across the Caribbean, A. palmata in Bonaire had relatively low expected heterozygosity, while A. cervicornis was greater than approximately half of other populations. Across Bonaire and for both coral species, we did not find evidence for genetic structuring among spatially separated subpopulations, indicating that both species are likely well-connected around the island. Together, these results demonstrate the effectiveness of RRFBs strategies to capture high genetic diversity and can be used to inform future initiatives on coral sexual breeding and assisted gene flow beyond Bonaire.

genetics↗

bioRxiv2021

Linking photoacclimation responses and microbiome shifts between depth-segregated sibling species of reef corals

Metazoans host complex communities of microorganisms that include dinoflagellates, fungi, bacteria, archaea, and viruses. Interactions among members of these complex assemblages allow hosts to adjust their physiology and metabolism to cope with environmental variation and occupy different habitats. Here, using reciprocal transplantation across depths, we studied adaptive divergence in the Caribbean corals Orbicella annularis and O. franksi. When transplanted from deep to shallow, O. franksi experienced fast photoacclimation, low mortality, and maintained a consistent bacterial community. In contrast, O. annularis experienced higher mortality, and limited photoacclimation when transplanted from shallow to deep. The photophysiological collapse of O. annularis in the deep environment was associated with an increased microbiome variability and reduction of some bacterial taxa. Differences in the symbiotic algal community were more pronounced between coral species than between depths. Our study suggests that these sibling species are adapted to distinctive light environments partially driven by the algae photoacclimation capacity and the microbiome robustness, highlighting the importance of niche specialization in symbiotic corals for the maintenance of species diversity. Our findings have implications for the management of these threatened Caribbean corals and the effectiveness of coral reef restoration efforts.

microbiology↗