Previous work

Genetic evidence and demography

Our analysis colonization patterns in seals (Gaggiotti et al.), exemplifies a major theme of my research. We developed a Bayesian analysis of genetic data to draw inferences about the demography of natural populations.  The method allowed us to characterize the origin of colonists from genetic data, even though there was minimal genetic differentiation between the potential source populations.  This was achieved by combining the small amounts of information from each pup, over a large number of pups.

Genetic evidence and viral evolution

Similar techniques have found application in a wide range of problems in the evolution of Varicella Zoster virus (VZV) in joint projects with Prof Judy Breuer.   VZV is responsible for chicken pox and shingles.  This work may help reveal how viruses respond to selection as they move within their host, and may have implications for the understanding of the evolution of  virulence in this and related viruses.

Genetic evidence and history

Our papers on the Mauritius Kestrel (Jim Groombidge et al) used Markov chain Monte Carlo methods  to overcome the computational problems of simultaneously estimating multiple parameters of biological interest.  This approach has been extended, in a paper on endangered skinks,  to estimate both relative population size and gene flow simultaneously (Nichols and Freeman); it improves on most existing methods for interpreting genetic data, which cannot distinguish these two effects.

Genetic evidence in forensic science

A controversial line of research was a project to quantify the differentiation between human populations at the genetic markers used in forensic science. These values are required to evaluate forensic evidence in court. David Balding and I developed the method currently used to deal with population differentiation in UK courts, and this has led to extensive consulting work.

Range expansion and inbreeding

The forensic strand of research has developed into diverse projects. They include the analysis of the human genetic patterns generated by the colonization of Europe and by the movements triggered by the development of agriculture (in a project with Mark Beaumont, Lounès Chikhi et al.). More recent human history and current practice have been studied in a project with Andy Overall on the effects of inbreeding in the UK Asian population (Overall et al.)


The analysis of geographic patterns is, in fact, a long-standing interest dating back to my PhD work with Godfrey Hewitt. A series of  publications on Iberian lizards with Octavio Paulo (Paulo et al) have a wider relevance, because they reveal major features of Iberian biogeography.  The theoretical tools for this sort of work is being extended by a current project.