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Walking Before Flying
An anonymous reader writes "BYU biostaticians report in Nature their genetic analysis of the insect, known as the 'walking stick', which apparently gives a contrapuntal example of reversible evolution. Called Dollo's Law, the principle holds that the same evolutionary pathway can never be backtracked, because of random mutations. But this insect class first had wings, lost them, then got them back again. So what's next for some humans: a happy return to dragging their knuckles?"
I guess this guy has looked at mutations in the stick insect genome and made inferences about the phylogenic tree relating the species. The underlying assumption in these sorts of approaches is known as the infinitely many sites assumption. This says that a mutation can only happen once in any place on the genome and once it has happened it cannot mutate back. This assumption, although reasonable in most cases, may not be valid here. It would be nice to know how much information was used from the genome in order to get an idea of the validity.
Mmmmm... convergent evolution... I'm under the impression that Dollo's Law refers to organisms evolving the exact same pathways to solve the same problem twice. When species evolve convergently, or even when one species re-evolves a trait, the same problem is usually solved in very different ways.
This site has the best definition that I was able to find, but I'm not sure how much stock I would place in its accuracy.