Comparative phylogeography as an integrative approach to historical biogeography

Phylogeography has become a powerful approach for elucidating contemporary geographical patterns of evolutionary subdivision within species and specie s complexes. A recent extension of this approach is the comparison of phylo geographic patterns of multiple co-distributed taxonomic groups, or 'compar ative phylogeography.' Recent comparative phylogeographic studies have reve aled pervasive and previously unrecognized biogeographic patterns which sug gest that vicariance has played a more important role in the historical dev elopment of modern biotic assemblages than current taxonomy would indicate. Despite the utility of comparative phylogeography for uncovering such 'cry ptic vicariance', this approach has yet to be embraced by some researchers as a valuable complement to other approaches to historical biogeography. We address here some of the common misconceptions surrounding comparative phy logeography, provide an example of this approach based on the boreal mammal fauna of North America, and argue that together with other approaches, com parative phylogeography can contribute importantly to our understanding of the relationship between earth history and biotic diversification.