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The expansion of populations into new territory is a common event in evolutionary history. Examples range from the growth of microbial biofilms on surfaces to the migration of prehistoric humans out of Africa. We are interested in the effects of evolutionary forces during such spatial expansions. We use the growth of colonies of the budding yeast Saccharomyces cerevisiae on agar surfaces as a model system. This spatial expansion leads to intriguing spatio-genetic patterns that can be visualized by fluorescence microscopy. The basic effect of spatial expansion is the formation of genetically uniform spatial sectors due to genetic demixing. We study how selection and species interactions modify this pattern. In particular, mutualistic interactions between yeast strains can prevent the genetic demixing.
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The expansion of populations into new territory is a common event in evolutionary history. Examples range from the growth of microbial biofilms on surfaces to the migration of prehistoric humans out of Africa. We are interested in the effects of evolutionary forces during such spatial expansions. We use the growth of colonies of the budding yeast Saccharomyces cerevisiae on agar surfaces as a model system. This spatial expansion leads to intriguing spatio-genetic patterns that can be visualized by fluorescence microscopy. The basic effect of spatial expansion is the formation of genetically uniform spatial sectors due to genetic demixing. We study how selection and species interactions modify this pattern. In particular, mutualistic interactions between yeast strains can prevent the genetic demixing.
