'Living fossil'? Not quite as its genome is actively evolving!

A group of scientists has decoded the first lingulid brachiopod genome, from Lingula anatina collected at Amami Island, Japan to find that this so-called 'living fossil' is still evolving.

Researchers from Okinawa Institute of Science and Technology Graduate University (OIST), Nagoya University and the University of Tokyo analyzed over 34,000 genes comprising the L. anatina genome, showing that despite Lingula's reputation as a "living fossil" its genome is actively evolving.

One would expect that living fossils would closely resemble their fossilised ancestors, not only in appearance but in genome as well. While that is close to true for coelacanths, other famous "living fossils", which have the slowest molecular evolutionary rate among vertebrates, the Lingula genome has been evolving rapidly, despite the lack of changes in appearance.

Shells of fossilised and living Lingula show considerable diversity in chemical structure. Analysis of the soft tissues of fossils also suggests morphological changes among lingulid brachiopods.

The authors of the paper also found significant changes in the genomic structure and gene families, contradicting the idea of a genuine "living fossil". Interestingly, the Lingula genes associated with basic metabolism show the slowest evolutionary change among lophotrochozoans.

The Lingula genome decoding sheds some light on the evolutionary history of brachiopods and lophotrochozoans as well as the origin of biomineralisation.

Researcher Noriyuki Satoh said that this is one step toward untangling the mysteries of animal evolution. The study highlights the fact that various animals have taken evolutionary paths independently from one another.

The paper is published in Nature Communications.