The Elkhorn coral, Acropora palmata, grows into large stands via polyp budding and fragmentation so that many colonies belong to the same clone or genet. During growth, mutations can accumulate in its cells and new research shows that the Ekhorn coral is able to pass these mutations onto to their sexual offspring. This is unlike most animals that prevent such a transfer from the body to reproductive cells. Credit: Iliana Baums
Key Points:
- Scientists have long believed that genetic mutations must occur in reproductive cells in order for them to have an advantageous evolutionary effect.
- A recent study spearheaded by Penn State biologists found that corals are able to pass on traits through mutations in somatic cells.
- Evolution via somatic cell mutations occurs at a faster rate and can help corals adjust to challenges presented by climate change.
An international team of scientists has made a discovery that upends long-held evolutionary beliefs about how animals pass on traits to their offspring. Scientists have long believed that genetic mutations have to transpire in reproductive cells in order to have an evolutionary impact. But now, a research team led by Penn State biologists has shown that Elkhorn corals pass can pass somatic mutations—changes to the DNA sequence that occur in non-reproductive cells—to their offspring.
The research team genotyped samples from 10 different locations on a large Elkhorn coral colony that had produced single-parent offspring, and samples from five neighboring colonies at nearly 20,000 genetic locations.
The results showed that all six of the separate coral colonies belonged to the same original coral genotype, meaning they were essentially clones derived from a single original colony through asexual reproduction and colony fragmentation. Thus, any genetic variation found in these corals would have been the result of somatic mutation. The team found a total of 268 somatic mutations in the samples, with each coral sample harboring between 2 and 149 somatic mutations.
The researchers then looked at the single-parent offspring from the parent Elkhorn coral colony and found that 50% of the somatic mutations had been inherited.
“Because corals grow as colonies of genetically-identical polyps, somatic mutations that arise in one coral polyp can be exposed to the environment and screened for their utility without necessarily affecting the entire colony,” said Iliana Baums, professor of biology at Penn State and leader of the research team. “Therefore, cells with potentially harmful mutations may die off and cells with potentially advantages mutations could thrive and spread as the coral colony continues to grow. If these mutations can then be passed on to offspring—as we have now demonstrated—it means that corals have an additional tool that might be able to speed up their adaptation to climate change.”
The exact mechanism of how the somatic mutations make their way into germline cells in the corals is still unknown, but the researchers intend to design more studies on the topic.