Scientists have discovered a pattern of gene activity, which allows some corals to survive in higher temperatures. This suggests a way to predict how different corals will react to warmer waters, which are expected to result from climate change over the coming decades.
The scientists published their findings in the journal Proceedings of the National Academy of Sciences¹. In the back reef of Ofu Island, in American Samoa, some of the Acropora hyacinthus corals are able to thrive in pools that experience daily heat fluctuations of up to 6°C. In order to find the molecular reason of this resilience, the researchers compared the gene activity in heat-resistant and heat-sensitive A. hyacinthus by measuring their transcriptome, the complement of RNA molecules transcribed from genes, under different sets of temperature.
The researchers found a suite of genes that while present in both populations, are more highly expressed in the temperature-resilient corals. These genes code for antioxidants as well as other proteins that these organisms deploy in response to heat shock.
The researchers found that the expression of hundreds of the genes changed in response to their tank water being heated from 29.2°C to 32.9°C. In heat-resilient corals, 60 of these genes are more highly expressed at the control temperature. This front-loaded gene expression could be what gives these corals a survival edge in changeable conditions.
The team is trying to determine whether the pattern of front-loaded genes is shared by other temperature-resilient coral species, in order to better understand the process and potentially develop a diagnostic test to identify sites around the world where coral might stand a better chance of surviving global climate change.
Reference: “Genomic basis for coral resilience to climate change” by Daniel J. Barshis, Jason T. Ladner, Thomas A. Oliver, François O. Seneca, Nikki Traylor-Knowles and Stephen R. Palumbi, 7 January 2013, Proceedings of the National Academy of Sciences.