Speciation, hybrid zones and phylogeography — or seeing genes in space and time


  • Godfrey M. Hewitt

    Corresponding author
    1. School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
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    • Dedication: This is dedicated to Bernard John my tutor, who first showed me the light of genetics and shared his joy in words and deeds.

Godfrey M. Hewitt. Fax: + 44 (0) 1603 592250; E-mail:g.hewitt@uea.ac.uk


The origins and development of the study of speciation, hybrid zones and phylogeography are outlined using evolutionary iconography. This traces the ideas in this field from Lamarck and Darwin through to the present as represented in diagrams and figures. A ‘tree of trees’ summarizes this growth and current vitality. The new facility to use various DNA sequences from nuclear, mitochondrial and chloroplast genomes to determine genetic variation throughout a species range is examined particularly. There is great genomic subdivision across species distributions, which can be interpreted in the light of the recent demonstrations of severe palaeoclimatic oscillations. Refugia 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 Homo sapiens through the last ice age. Some suggestions are made for future research directions.