Scientists have discoverd the “key” gene to colonize on freshwater

Miguel Leal, MARE scientist, is the co-author of an article published on Science this Friday, “A key metabolic gene for recurrent freshwater colonization and radiation in fishes”

When organisms evolve to occupy new environments, what adaptations are necessary for the transitions, and how predictable are these solutions when the transitions occur repeatedly? The asks on the beginning of the article. 

The study concludes that, because of the deficiency in docosahexaenoic of colonized marine fish, asingle adaptive genetic innovation has repeatedly allowed them to colonize and diversify in freshwater. Although previous studies on evolutionary transitions and subsequent radiations to new ecological niches have largely focused on morphology, new study links ecology, physiology, and genetics through a dietary adaptation. 

A number of copies of a single gene, fatty acid desaturase 2 (Fads2), in a marine- adapted lineage of threespine stickleback enables the fish to survive on a freshwater diet. Fads2 encodes an enzyme crucial for fatty acid synthesis, so increasing the number of Fads2 genes in a fish genome compensates for the dietary dearth of fatty acids such as docosahexaenoic acid (DHA) in freshwater.