100 million years ago, salmon doubled every gene they had — scientists have now mapped what happened next

About 100 million years ago, the ancestor of salmon and trout did something extreme: it copied its entire genetic code, doubling every gene at once. A team led by the Roslin Institute at the University of Edinburgh and the Norwegian University of Life Sciences, including Dr Rose Ruiz Daniels of the University of Stirling's Institute of Aquaculture, has now mapped how that doubling played out — building a large dataset across Atlantic salmon and rainbow trout, from early development to adulthood, showing which genes switch on, where, and when, both for genes that existed before the doubling and those it created. The headline finding is a kind of discipline: even after a total duplication, how genes are used stayed constrained by the developmental processes shared across many species. The maps the team built are a working tool — for research into farmed fish that feed millions, and for understanding gene evolution far beyond the river.

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