Our findings highlight that even rare hybridization events can have lasting adaptive consequences, shaping biodiversity in dynamic environments like the North Atlantic.

#Hybridization #Speciation #Genomics #PopGen

This adds to a growing body of evidence that hybridization can be a creative force in evolution, transferring useful alleles across species boundaries.

Together, these results show that gene flow from a distant relative helped Baltic herring adjust to a low-salinity, low-light environment—a striking case of adaptive introgression in a marine fish.

Several of the introgressed genes have clear functional relevance:

THRB affecting visual development, the Pacific variant may enhance vision under the red-shifted light of the Baltic’s shallows.

SEC16B, involved in lipid metabolism; possibly improving energy storage during long, cold winters.

We found that only 0.29% of the Atlantic herring genome shows signs of introgression from Pacific herring.
Yet remarkably, that fraction includes about 10% of all the most strongly selected loci in Baltic populations.

Ancient hybridization provided adaptive raw material for a new environment.

Atlantic and Pacific herring diverged about 3 million years ago, but they re-encountered each other in the Arctic after the last Ice Age and hybridized.

That brief contact left a lasting legacy in the genome of Baltic herring.

Interested in this as well… but I do not have a good answer!