Molecular studies reveal highly ordered geographic patterns in plant and animal distributions. The tropics illustrate these patterns of community immobilism leading to allopatric differentiation, as well as other patterns of mobilism, range expansion, and overlap of taxa. Integrating Earth history and biogeography, Molecular Panbiogeography of the Tropics is an alternative view of distributional history in which groups are older than suggested by fossils and fossil-calibrated molecular clocks. The author discusses possible causes for the endemism of high-level taxa in tropical America and Madagascar, and overlapping clades in South America, Africa, and Asia. The book concludes with a critique of adaptation by selection, founded on biogeography and recent work in genetics.