changes or mutations ... perhaps clarifying the terms in the process.

Pardon the intrusion of a layman, but I thought the length of the phylogeograpic thread was extended by the continued explanation of evolution as mutation and selection as if mutation came from a single cause. So that responders kept hammering about single-source 'damage' leading to reduction in diversity. With knowledge of the multiple ways to alter the basic DNA, they might have grasped the significance of mutation and given it a little slack. Explanations of bacterial remnants in cells might have helped, too. OTOH,this may have been covered and it slipped by me.