Extrapolating Cladistic Biogeography: A Brief Comment on van Velleret al.(1999, 2000, 2001)

Cladistic biogeography aims to find congruence (common patterns among area relationships) among taxon‐area cladograms. Not all areagrams are congruent, and ambiguity needs to be either reduced or resolved in order for a common biogeographic pattern to emerge. Recent papers by van Veller et al. (1999, Cladistics 15, 393–406; van Veller et al. 2000, Cladistics 16, 319–345; van Veller et al. 2001, Cladistics ) suggest that ambiguity is the result of isolation mechanisms other than vicariance. That is, identifying such mechanisms in a monophyletic group or areagram and by combining two or more areagrams using assumptions 0, 1, or 2 may result in common patterns. Under such a hypothesis van Veller et al. (1999, 2000, 2001) suggest that ambiguity is congruent and removal of it decreases explanatory power. Assumption 0 differs in all other approaches as it resolves ambiguity using taxon and not area relationships , contrary to the aims of cladistic biogeography.