Evolutionary biologists have puzzled over why nature, with vast genetic resources at its disposal, sometimes seems stuck in a rut. Against the odds, separate species and populations independently evolve the same solutions to life’s challenges, and the same genes are recruited to mutate and enable certain adaptations again and again. Now researchers at Stanford University think they have found part of the answer, at least for the fish called three-spine sticklebacks (Gasterosteus aculeatus).
According to a recent study described in Science, the stickleback’s DNA has fragile “hot spots” that are predisposed to break and mutate more often, with an accompanying loss of traits. The result is that these fish rapidly evolve the same adaptation—the loss of a pair of fins on their pelvis—repeatedly.