"Comparative phylogeographic studies usually involve a) documenting a phylogeographic pattern and b) recognizing that the same pattern is congruent in multiple species.

But what if species histories are only sort of congruent? Perhaps they share one major splitting event but not later events. Or maybe the phylogenies are topologically congruent but on very different timescales. It would be great to measure the degree of phylogeographic discordance among species."

A new (quantitative!) method for comparative phylogeography
http://www.molecularecologist.com/2016/05/a-new-quantitative-method-for-comparative-phylogeography/