Geographical diversification of tribes epilobieae, gongylocarpeae, and onagreae (Onagraceae) in North America, based on parsimony analysis of endemicity and track compatibility analysis

Tribes Epilobieae, Gongylocarpeae, and Onagreae, a monophyletic branch in the family Onagraceae, comprise genera endemic to or having their major basal radiation in the Madrean Floristic Region of southwestern North America. Parsimony analysis of endemicity (PAE) and panbiogeography (track compatibility analysis) were performed in order to seek an historical explanation for the patterns of high diversity and endemicity for the group in this region. Twentyone areas of endemism are delimited, based on previous biogeographic schemes and presence of endemic plant and animal taxa. Based on distributional data on 173 species, a strict consensus PAE cladogram shows four main groups of areas: northern North America, the central Mexican areas, western North America, and eastern North America. Track compatibility analysis resulted in two strongly supported generalized tracks: one includes eastern North America, and the other western North America. PAE and panbiogeographical analyses of the distributional patterns of these taxa suggest a close relationship of eastern and western North America, with both areas more related to the Neotropics than to the Palearctic, and a rather weak association between northern North America and Asia. The discovery of two tracks in eastern and western North America for Epilobieae, Gongylocarpeae, and Onagreae reveal little relationship of North America with Asia or other continents. These tribes display a distinet but contemporaneous biogeographical history that differs from those of the Holaretic. These eastern and western tracks show that ancestral biotas existed on each side of North America, with the species of each track sharing a common history.