Selfish genes, or shellfish genes?
Often known as the Great Scallop, King Scallop or Coquille St Jacques, the scallop Pecten maximus is widespread around northern Europe, and is an important human food source.
The genome of this species has just been made available (see Kenny et al. 2020 and this dnazoo.org webpage) as part of a collaboration with the Wellcome Sanger 25 Genomes project. As well as being the best assembled bivalve genome to date, it contains a large number of surprises. Approximately 70,000 of them, in fact - an exceptionally high number of genes packed into a relatively normal (circa 1.1 Gbp) sized genome. This is more than double the number of genes found in humans and in most commonly studied species!
These genes have been generated from widespread gene duplication, together with relatively little gene loss. The cause of this is not yet known, but echos what has been seen in some other mollusk genomes (e.g. Li et al 2018). Scallops therefore seem to need lots of new genes!
The genome contains a number of clues that will be useful for managing fisheries of this species. For example, Scallops are resistant to domoic acid, which they can accumulate when filter feeding. A potential cause of this resistance has been identified in our data, which could stop people from getting sick with Amnesic shellfish poisoning.
Scallops also have beautiful and unique eyes, and are some of the most mobile shellfish (able to swim surprisingly big distances). The Pecten maximus genome will therefore be interesting to evolutionary biologists, pharmaceutical companies, and anyone who likes to eat seafood. It is sure to be the basis for many sorts of work in the future - the world is its oyster (oops, no, scallop!).
Kenny et al. 2020 Scallop preprint: https://www.biorxiv.org/content/10.1101/2020.01.08.887828v1.full
Li, C., Liu, X., Liu, B., Ma, B., Liu, F., Liu, G., Shi, Q. and Wang, C., 2018. Draft genome of the Peruvian scallop Argopecten purpuratus. GigaScience, 7(4), p.giy031.