UNIVERSITY PARK, Pa. — New genome-sequence research data show that Caribbean corals that have survived mass-extinction events caused by environmental change can rebound and expand their populations.
An international team of researchers, led by scientists at Penn State University, sequenced the genomes of three species of corals in the genus Orbicella and used the data to model the population histories of these corals over the past several million years. Despite massive reductions in the coral populations following the onset of glaciation in the Northern Hemisphere between 1 and 2 million years ago — an event that caused the extinction of many other Caribbean coral species — these Orbicella coral populations rebounded and expanded into new habitats opened by the mass-extinction event.
“Corals are extremely ecologically and economically important, so understanding how their populations responded to environmental change historically is crucial for current conservation efforts,” said Mónica Medina, associate professor of biology at Penn State and one of the lead authors of the research. “Our study of living corals confirms fossil evidence that suggested that coral populations can recover after environmental disasters, and further suggests that current reef deterioration can be reversed if environmental stresses can be reduced.”
The international research team included scientists from institutions in the United States, Australia, Mexico and Japan. A paper describing the research appeared online Nov. 17 in the journal Current Biology.
The researchers sequenced the genomes of the three surviving Orbicella species, O. annularis, O. faveolata and O. franksi. The Orbicella corals have a rich fossil record that shows an increase in species diversity about 2.5 to 3.5 million years ago, followed by a massive extinction event that wiped out half of the species between 1 and 2 million years ago. All but three of the remaining species went extinct over the next million years. The team used their new genomic data to reconstruct the population histories of the three modern Orbicella species over this time period, filling in gaps in the fossil record and showing that given enough time, some corals can recover after environmental catastrophes.