Ancient 'Living Fossil' is Evolving Genetically, But Looks the Same

A group of scientists have discovered that a mysterious "living fossil" may not have changed much on the outside, but it's definitely evolved genetically. Researchers have found that Lingula anatine has a genome that's actively evolving.

Brachiopods, like L. anatine, are often confused with molluscs; however, the resemblance is superficial. Unlike bivalves that have shells on the sides of their bodies, brachiopod shells are on the top and bottom. As a result, the planet of symmetry in a bivalve runs along the hinge. This causes the two valves to be mirror images of one another. In brachiopods, the plane of symmetry is perpendicular to the hint, so that the halves of the valves mirror each other.

Brachiopods are actually one of the first known examples of animal biomineralization. This is a process whereby living organisms stiffen or harden tissues with minerals. The earliest discovered brachiopod fossils date to the early Cambrian period, which is about 520 million years ago.

Now, researchers have taken a closer look at this particular brachiopod in order to better understand the evolutionary origin of these creatures and their relations to other species.

The researchers analyzed over 34,000 genes comprising the L. anatine genome. This revealed that despite this species' reputation as a "living fossil," its genome is actively evolving.

"At the molecular level, brachiopods are very similar to molluscs. Both are protostomes-their embryos form mouths first and anuses thereafter," said Yi-Jyun Luo, first author of the new paper, in a news release. "However, brachiopod embryonic development is very different from that of molluscs: it resembles that of deuterostomes, in which embryos form anuses first and mouths second. The results of the Lingula genome project will help future research of these differences and the roles that specific genes play in development of various brachiopod body structures."

The findings are published in the journal Nature Communications.

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