This Special Issue of Molecular Ecology contains a selection of papers from participants in the ‘Phylogeography, Hybridization and Speciation’ meeting held at the Centre Paul Langevin, Aussois, France in April 2000. The meeting was conceived as a 60th birthday present for Professor Godfrey Hewitt, of the University of East Anglia, Norwich, UK, to recognize his seminal contributions to these three interconnected fields. Many of those present, and many more who were not able to attend, owe a debt of gratitude to Godfrey. For his numerous former students and research assistants he has been, and continues to be, a friend and supporter as well as an academic leader. For those from around the world who know him only from conferences or from his publications, he is an inspiration.

This is an exciting time for the subject area, largely because of the new opportunities made available by advances in molecular ecology. Papers in this issue show clearly how powerful these methods can be in elucidating historical relationships among populations and species, in tracing patterns of postglacial colonization, and in dissecting the genetic basis of phenotypic differentiation or reproductive isolation. However, more traditional studies retain an ability to provide insights into evolutionary problems, and this is also reflected in this Special Issue. As molecular approaches develop further and generate ever larger data sets, more sophisticated analyses are needed to provide the most robust tests of alternative hypotheses or to extract the maximum amount of information. This is an area where there is still much to be learned. A hallmark of Godfrey Hewitt’s work has always been the integration of diverse approaches. A full understanding of a complex issue such as speciation requires data from ecology, palaeoecology, systematics, cytogenetics, and evolutionary theory as well as molecular biology. We hope that the papers in this issue reflect this breadth of Godfrey’s interests and influence, and the excitement we felt at the meeting.

Mike Ritchie and Roger Butlin greatly acknowledge the help of Loren Rieseberg and Harry Smith in offering to publish these papers in a Special Issue of Molecular Ecology and for their editorial help. Most of all, we are grateful to all the authors and referees for their efforts. The Genetical Society and the University of East Anglia provided financial help for the meeting.