(ORDO NEWS) — It turned out that Elkhorn corals (Acropora palmata) can pass on mutations accumulated in the cells of the body to their offspring.
As a rule, the transfer of mutations is possible only through germ cells, and scientists do not fully understand how corals manage to overcome this limitation.
However, such a mechanism likely allows corals to test the usefulness of mutations faster and better adapt to changing habitats.
Scientists from the University of Pennsylvania (USA) have made a discovery that challenges more than a century of ideas about evolution.
They showed that Elkhorn corals ( Acropora palmata ) pass on to their offspring somatic mutations changes in the DNA sequence that occur not in the sex cells, but in the cells of the rest of the body.
For most animals, a new mutation can only lead to an evolutionary change if it occurs in a germ cell, such as an egg or sperm cell.
It was believed that mutations occurring in other parts of the body, that is, in somatic cells, could not be inherited. But corals seem to have a way around this limitation.
In most organisms, the reproductive cells separate from the rest of the body cells early in development. Mutations in them contribute to the evolution of the species, but this is not a very fast process.
Corals are able to reproduce both by budding and sexually. In the Elkhorn coral, in addition, some eggs can turn into viable offspring without the participation of a second coral.
This is what allowed scientists to look for potential somatic mutations in the parent coral and track them in its offspring.
The researchers genotyped coral samples collected from ten locations in one large colony representing the offspring of a single parent and five adjacent colonies.
The results showed that all six individual colonies belonged to the same original genotype, that is, they were clones that appeared from the germ cells of one individual or in the process of its budding.
Thus, any genetic variation found in these corals would be the result of a somatic mutation.
The team identified a total of 268 somatic mutations in the samples, with each sample containing between two and 149. With 50% of the somatic mutations being inherited.
The exact mechanism of this process is not yet known, but the authors of the work suspect that the separation between coral body cells and sex cells may be incomplete, and some somatic cells may turn into sex cells, allowing somatic mutations to be passed on to offspring.
Because corals grow as colonies of genetically identical polyps, somatic mutations that occur in one polyp are exposed to the environment and tested for “usefulness” without affecting the rest of the colony.
Cells with potentially harmful mutations can die, while cells with potentially beneficial mutations pass them on as the colony grows, accelerating the coral’s adaptation to environmental conditions.
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