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Jellyfish and relatives repeatedly evolved the same genetic changes across 600 million yearsWe compared thousands of genes across 86 species of jellyfish and their relatives to ask how often natural selection appears to have produced the same changes in proteins in different lineages. These repeated changes were surprisingly widespread. They were somewhat less common in more distantly related species, but remained more frequent than expected by chance even in lineages that separated more than 600 million years ago. Yet pairs of species that had independently evolved the same conspicuous traits—eyes, loss of the jellyfish stage, or upright colonies—did not share more repeated protein changes than other pairs. Instead, the changes were concentrated in genes involved in metabolism, immunity, and processing foreign chemicals. These results suggest that evolution often repeats at the molecular level, but this repetition reflects complex interactions between organisms and their environments rather than being tightly linked to the same obvious traits.link.growkudos.com