The genetic model predicts the mass death of corals

Sensitivity of individual corals to high temperatures is determined by hereditary factors. To such conclusion researchers analyzed 237 samples of the coral Acropora millepora from the Great Barrier reef. In this case the decisive role is played not by any specific genes, and their combination. The data obtained formed the basis of models which predict the vulnerability of coral reefs and will help to develop measures for their protection. However, even the use of genetics will only buy some time against the main threat to corals — climate change. The results of a study published in the journal Science.

Corals are extremely sensitive to ambient temperature. When the water becomes too warm, they lose their symbiotic algae, dinoflagellates and discolored. If conditions remain unfavorable for too long, the corals die.

In recent decades amid climate change, mass bleaching of coral reefs is increasingly: for example, the Great barrier reef only in the last five years, has experienced three such episodes. If the planet continues to warm, coral reefs worldwide are at risk to disappear during this century.

However, not all coral species are equally vulnerable to discoloration. Moreover, even among members of the same species sensitivity to high temperatures varies. A team of researchers led by Zachary fuller (Zachary L. Fuller) of Columbia University decided to find out what are the genetic basis of this variability.

Specialists conducted a genome-wide analysis of 237 samples of the coral Acropora millepora, taken at 12 sites of the Great Barrier reef at the peak of bleaching in 2017. Genetic data were compared with the degree of damage suffered by the individual colonies.

It turned out that tolerance to high temperatures is ensured not by individual genes but combinations of many genes, each of which gives a relatively small effect. Based on polygenic evaluation and data about genomes of symbiotic algae and characteristics of the environment, the authors were able to create a model that predicts the vulnerability of certain evolutionary lines A. millepora to climate change. It can be used to identify the most vulnerable reefs, or take samples of coral for artificial rearing.

Researchers believe that a similar approach can be used to create models that predict the risk of bleaching in other species of corals. However, genetics is not able to save coral reefs from extinction, the authors say. To give these rich ecosystems, the chances of survival, we need to reduce greenhouse gas emissions.

Some corals in response to high temperature does not fade, and become unusually bright color. The researchers were able to establishthat it is a kind of analogue of sunscreen. Proteins providing the “acid” colors, protect the coral from UV radiation, which increases the chances of the return of the symbionts.

Sergey Knee High

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