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Laurent Excoffier
Computational and Molecular
Population Genetics Group
University of Bern
Group Webpage

What do we do?

At the Computational and Molecular Population Genetics (CMPG) Group we are developing new methodologies for the simulation and analysis of molecular polymorphisms within species, with a particular focus on humans. We also develop and maintain the Arlequin software, a popular package for the analysis of multi-locus genetic diversity within and between populations as well as statistical methods to reconstruct and infer evolutionary processes from genomic data. The team focuses on the effect of range expansions on genomic and functional diversity, and the detection of signatures of adaptation and selection at the molecular level.

Highlights 2015

In 2015, our group continued our study on the effect of spatial range expansions on the functional diversity of a species. Using a mixture of computer simulations and analytical modelling, we demonstrated that populations which expanded their range should present an excess of deleterious mutations due to inefficient purifying selection. This mutation load should then correlate positively with the distance from their place of origin. The group showed that such a mutation load was indeed present in humans by contrasting the genomic diversity of African and non-African populations. A clear gradient of mutation load from Africa to the Americas was observed, and probably occurred during the migration of modern humans out of Africa about 50,000 years ago.

Main publications 2015

  • Henn BM et al. Distance from Sub-Saharan Africa Predicts Mutational Load in Diverse Human Genomes. PNAS 2015;113:E440-9.
  • Peischl S et al. Expansion load and the evolutionary dynamics of a species range. Am Nat 2015;185:E81-E93.
  • Peischl S et al. Expansion load: recessive mutations and the role of standing genetic variation. Mol Ecol 2015;24:2084-2094.

Our research topics: