Palaeoclimate ocean conditions shaped the evolution of corals and their skeletons through deep time

Andrea M. Quattrini, Biology Department, Harvey Mudd College, Claremont, CA, USA. quattrinia@si.edu.
Estefanía Rodríguez, Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA.
Brant C. Faircloth, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
Peter F. Cowman, ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.
Mercer R. Brugler, Division of Invertebrate Zoology, American Museum of Natural History, New York, NY, USA.
Gabriela A. Farfan, Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington DC, USA.
Michael E. Hellberg, Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
Marcelo V. Kitahara, Institute of Marine Science, Federal University of São Paulo, Santos, Brazil.

Abstract

Identifying how past environmental conditions shaped the evolution of corals and their skeletal traits provides a framework for predicting their persistence and that of their non-calcifying relatives under impending global warming and ocean acidification. Here we show that ocean geochemistry, particularly aragonite-calcite seas, drives patterns of morphological evolution in anthozoans (corals, sea anemones) by examining skeletal traits in the context of a robust, time-calibrated phylogeny. The lability of skeletal composition among octocorals suggests a greater ability to adapt to changes in ocean chemistry compared with the homogeneity of the aragonitic skeleton of scleractinian corals. Pulses of diversification in anthozoans follow mass extinctions and reef crises, with sea anemones and proteinaceous corals filling empty niches as tropical reef builders went extinct. Changing environmental conditions will likely diminish aragonitic reef-building scleractinians, but the evolutionary history of the Anthozoa suggests other groups will persist and diversify in their wake.

This paper has been withdrawn.