Any luck you'd talk about this at MVIF? 1 question: Imagine env changes and residue at pos 100 is selected. Then env changes back, but pos 100 is not reverted, instead pos 102 is (another path back to orig phenotype). Then did this phenotypic reversion result in higher dN/dS not lower?

put another way, do you have to quantify/distinguish between "perfect" reversions (at the exact AA level, seem to decrease dN/dS) and "imperfect" reversions (mutating other residues in the same gene to revert that gene's phenotype, would increase dN/dS further)?