Morphological traits of reef corals predict extinction risk but not conservation status

Aim The current assessment of extinction risk in reef corals by the International Union for Conservation of Nature (IUCN) has been criticized, because coral life-history traits associated with resilience are not reflected in the conservation status. We aimed to carry out a quantitative assessment of the link between reef coral traits and species extinction risk informed by extinctions of reef corals observed in the fossil record. Location Global. Time period Plio-Pleistocene and present day. Major taxa studied Scleractinian reef corals. Methods We used morphological traits, phylogenetic information and evidence of extinction during the Plio-Pleistocene to predict the extinction risk of contemporary reef corals. Our model was trained using 138 Caribbean fossil coral species and an automatic machine learning algorithm. We then used this model to predict the extinction risk of 674 modern coral species. Results Model validation confirmed 77% accuracy in predicting extinction risk of fossil corals. Extinction risk predicted by our model showed a near-random (57%) match with the IUCN conservation status. Our model also suggested that corals in the Least Concern or Near Threatened categories might be at higher risk of extinction than currently believed. Main conclusions Morphological traits of fossil corals linked to their extinction risk in the Plio-Pleistocene Caribbean Sea are known to reflect the vulnerability of extant corals. However, the results from our fossil-calibrated model do not match the IUCN assessment of reef corals, with increased overall extinction risk. This does not necessarily indicate near-future extinction risk, because fossil extinctions are spread over thousands of years. However, we show the applicability of using fossil data to inform the extinction risk of modern corals and recommend that future assessments of extinction risk of reef corals should consider incorporating the relationship between morphological traits and resilience, calibrated by fossil data, to maximize the utility of the extinction risk assessment.

Automated summary

The study aimed to quantitatively assess the link between reef coral traits and species extinction risk using fossil records. Results showed that morphological traits of fossil corals are related to their extinction risk, suggesting the importance of considering the relationship between morphology and resilience in future extinction risk assessments. The model developed for predicting extinction risk of modern corals based on fossil data indicated discrepancies with the IUCN assessment, highlighting the potential for using fossil data to inform the extinction risk of modern corals.