Speciation, hybrid zones and phylogeography - or seeing genes in space andtime

The origins and development of the study of speciation, hybrid zones and ph ylogeography are outlined using evolutionary iconography. This traces the i deas in this field from Lamarck and Darwin through to the present as repres ented in diagrams and figures. A 'tree of trees' summarizes this growth and current vitality. The new facility to use various DNA sequences from nucle ar, mitochondrial and chloroplast genomes to determine genetic variation th roughout a species range is examined particularly. There is great genomic s ubdivision across species distributions, which can be interpreted in the li ght of the recent demonstrations of severe palaeoclimatic oscillations. Ref ugia and postglacial colonization routes are proposed for several organisms across Europe. The role of geography in speciation through the Pleistocene is considered. These emerging principles and analyses are applied to data available on a variety of organisms in other regions of the world, such as the Arctic, North America and the Tropics, and including the progress of Ho mo sapiens through the last ice age. Some suggestions are made for future r esearch directions.