Submitted via IRC for SoyCow8093
Mexican tetra swam from surface waters into their caves around 1.5 million years ago. Like naked mole rats—another species that lives underground, in perennial darkness—they have no eyes. But whereas key genes controlling eye development in naked mole rats have mutations that inactivate them, there are no such inactivating mutations in the genes of the Mexican cave fish.
But mutations aren't the only way to change gene activity, and new research suggests a different explanation for the fish's lack of eyes. Epigenetic regulation is a means of controlling gene activity that does not alter the DNA sequence of the genes themselves. Genes undergoing epigenetic regulation can still make normal proteins, but the amount of the protein they make is modulated.
One method of epigenetic regulation is the addition of methyl groups to the DNA that controls the activity of specific genes. It is efficient, since it can be used to alter a whole bunch of genes at once. And it seems to explain the Mexican cave fish eye degeneration that has occurred over the past million years—a proverbial blink of an eye in evolutionary terms.
An epigenetic mechanism for cavefish eye degeneration (DOI: 10.1038/s41559-018-0569-4) (DX)
(Score: 2) by EventH0rizon on Tuesday June 05 2018, @02:51AM
That is a fascinating finding if it plays out as the researchers suggest.
And it's the closest we may ever get to real Lamarckian evolution.
I think I can hear Stephen Jay Gould turning in his grave....