Evolutionary Traits that Enable Scleractinian Corals to Survive Mass Extinction Events

Gal Dishon,Gilad Guy,Michal Grossowicz,Dan Tchernov,David F Gruber,Michael Krom

doi:10.1038/s41598-020-60605-2

Abstract

Scleractinian “stony” corals are major habitat engineers, whose skeletons form the framework for the highly diverse, yet increasingly threatened, coral reef ecosystem. Fossil coral skeletons also present a rich record that enables paleontological analysis of coral origins, tracing them back to the Triassic (~241 Myr). While numerous invertebrate lineages were eradicated at the last major mass extinction boundary, the Cretaceous-Tertiary/K-T (66 Myr), a number of Scleractinian corals survived. We review this history and assess traits correlated with K-T mass extinction survival. Disaster-related “survival” traits that emerged from our analysis are: (1) deep water residing (>100 m); (2) cosmopolitan distributions, (3) non-symbiotic, (4) solitary or small colonies and (5) bleaching-resistant. We then compared these traits to the traits of modern Scleractinian corals, using to IUCN Red List data, and report that corals with these same survival traits have relatively stable populations, while those lacking them are presently decreasing in abundance and diversity. This shows corals exhibiting a similar dynamic survival response as seen at the last major extinction, the K-T. While these results could be seen as promising, that some corals may survive the Anthropocene extinction, they also highlight how our relatively-fragile Primate order does not possess analogous “survival” characteristics, nor have a record of mass extinction survival as some corals are capable.

Highlights

Scleractinian corals represent an ideal taxon to serve as a model for describing past and predicting future environmental trajectories of mass extinctions
Examination of various coral traits represented in the fossil record showed pronounced features related to the K-T mass extinction event (Fig. 1)
Understanding the effects of biological traits on coral survival and future community structure is a matter of high priority[41,45], both for what it predicts for the future of coral reefs and as a general model for the selective survival of various biological communities

Summary

Introduction

Scleractinian corals represent an ideal taxon to serve as a model for describing past and predicting future environmental trajectories of mass extinctions. The earth has experienced five major mass extinction events (“The Big Five”) since the Cambrian period, each resulting in the loss of more than three-quarters of species biodiversity over a geologically short time interval. Increased atmospheric CO2 concentrations are causing measurable ocean acidification[26] This together with habitat fragmentation, pollution, overfishing and overhunting, the introduction of invasive species and pathogens, and expanding human biomass represents a combination of global wide extreme stressors combining in unprecedented ways for most species[6,27]. Stony corals are sensitive and are heavily impacted by direct human interferences (e.g. overfishing, pollution, coastal development and tourism damage), as well as warming and ocean acidification They are predicted to suffer more than 30–50% extinction in the coming decades and century, respectively[5,24]

Methods

Results

Conclusion