From Frederick Colbourne:

Re: When evolution isn’t so slow and gradual (June 2): Swanne Pamela Gordon’s study indicated that adaptive changes might have been picked up by guppies in new environments. Clearly, the changes were transmitted to the descendants of the guppies that were observed at the beginning of the 8-year experiment. But has the DNA changed structurally (genetics) or has only the expression of the characteristics (epigenetics) changed?

Does this experiment tell us anything about the rate of Mendelian genetic inheritance or does it only contribute to epigenetics? Other experiments have suggested that epigenetic changes revert once conditions change. If this experiment has observed only epigenenetic changes, it does not inform theories of Darwinian evolution of descent by natural selection but instead confirms previous epigenetic research in other species.