PALEOBIOGEOGRAPHY: FROM EVOLUTION TO GLOBAL CHANGE

Paleobiogeography is that scientific discipline that seeks to determine the relationship between the evolution of the Earth and its biota. It is a discipline with a rich scientific legacy. Recently, an analytical technique has been developed for use with fossil taxa that requires knowledge of phylogenetic patterns in several groups; congruent patterns among groups can be identified and potentially related to tectonic or climatic changes. This technique uses a modified version of Brooks Parsimony Analysis to reconstruct episodes of vicariant speciation and range expansion (geo-dispersal). Only if both vicariance and geo-dispersal are considered in concert can the reconstructed paleobiogeographic patterns be meaningful because there are geological and climatic processes that produce each of these effects. This method has been applied to studies spanning the Phanerozoic. For example, biogeographic patterns from Early Cambrian trilobites suggest that metazoan diversification was underway by the late Neoproterozoic. Moreover, they indicate a tectonic link between Laurentia, Amazonia, Avalonia, and northwestern Africa. In addition, biogeographic studies of modern North American freshwater molluscs using phylogenetic information from molecular markers indicate that the topology of Plio-Pleistocene river drainages more fundamentally influenced evolution than late Pleistocene and Holocene climate changes. One of the fundamental patterns emerging from paleontology in the last twenty years is the tie in between earth history change and evolution. Paleobiogeography is important because it can be used to quantify this link and also to identify specific tectonic events which most influenced evolution during particular time intervals. Future challenges for paleobiogeography include incorporating extinction and preservation probabilities into analytical methods.