Research Repository

A modern scleractinian coral with a two-component calcite–aragonite skeleton

Stolarski, Jaroslaw and Coronado, Ismael and Murphy, Jack G and Kitahara, Marcelo V and Janiszewska, Katarzyna and Mazur, Maciej and Gothmann, Anne M and Bouvier, Anne-Sophie and Marin-Carbonne, Johanna and Taylor, Michelle L and Quattrini, Andrea M and McFadden, Catherine S and Higgins, John A and Robinson, Laura F and Meibom, Anders (2020) 'A modern scleractinian coral with a two-component calcite–aragonite skeleton.' Proceedings of the National Academy of Sciences, 118 (3). ISSN 0027-8424

[img]
Preview
Text
2013316117.full.pdf - Published Version
Available under License Creative Commons Attribution Non-commercial No Derivatives.

Download (2MB) | Preview

Abstract

Until now, all of the ca. 1,800 known modern scleractinian coral species were thought to produce skeletons exclusively of aragonite. Asymbiotic Paraconotrochus antarcticus living in the Southern Ocean is the first example of an extant scleractinian that forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite. This discovery adds support to the notion that the coral skeletal formation process is strongly biologically controlled. Mitophylogenomic analysis shows that P. antarcticus represents an ancient scleractinian clade, suggesting that skeletal mineralogy/polymorph of a taxon, once established, is a trait conserved throughout the evolution of that clade.One of the most conserved traits in the evolution of biomineralizing organisms is the taxon-specific selection of skeletal minerals. All modern scleractinian corals are thought to produce skeletons exclusively of the calcium-carbonate polymorph aragonite. Despite strong fluctuations in ocean chemistry (notably the Mg/Ca ratio), this feature is believed to be conserved throughout the coral fossil record, spanning more than 240 million years. Only one example, the Cretaceous scleractinian coral Coelosmilia (ca. 70 to 65 Ma), is thought to have produced a calcitic skeleton. Here, we report that the modern asymbiotic scleractinian coral Paraconotrochus antarcticus living in the Southern Ocean forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite. P. antarcticus and Cretaceous Coelosmilia skeletons share a unique microstructure indicating a close phylogenetic relationship, consistent with the early divergence of P. antarcticus within the Vacatina (i.e., Robusta) clade, estimated to have occurred in the Mesozoic (ca. 116 Mya). Scleractinian corals thus join the group of marine organisms capable of forming bimineralic structures, which requires a highly controlled biomineralization mechanism; this capability dates back at least 100 My. Due to its relatively prolonged isolation, the Southern Ocean stands out as a repository for extant marine organisms with ancient traits.Mitogenome sequences data have been deposited in GenBank (MT409109). All other study data are included in the article text and supporting information.

Item Type: Article
Uncontrolled Keywords: biomineralization, calcium carbonate, scleractinian corals, evolution, Southern Ocean
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 15 Dec 2020 18:53
Last Modified: 25 Feb 2021 10:15
URI: http://repository.essex.ac.uk/id/eprint/29369

Actions (login required)

View Item View Item