Salmon are shrinking and it shows in their genes

The gene version that tells salmon to mature at a later age and thus grow bigger is becoming less common, while the version that urges them to hurry up and get on with it is getting more prevalent. Behold evolution in action.

Male salmon are maturing earlier and becoming smaller, and it shows in their genes. This was the discovery of a study that examined scale samples from salmon in the River Teno in Northern Finland over a 40-year period, and looked at the population genetic profile of a gene that determines salmon’s age of maturity and size. The results show that the ‘big salmon gene version’ has become rarer in the population over time, and has been replaced by the ‘small salmon gene version’.

The study, conducted by scientists from the University of Helsinki in co-operation with Natural Resources Institute Finland and the University of Turku, was published in the journal Nature Ecology and Evolution and was featured on the magazine’s November issue’s cover.

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