Environmental heterogeneity enhances clonal interference |
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Authors: | Campos Paulo R A Neto Pedro S C A de Oliveira Viviane M Gordo Isabel |
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Institution: | Departamento de Física, Universidade Federal Rural De Pernambuco 52171-900, Dois Irmãos, Recife-Pe, Brazil;E-mail:;Departamento De Estatística e Informática, Universidade Federal Rural de Pernambuco 52171-900, Dois Irmãos, Recife-PE, Brazil;Instituto Gulbenkian de Ciência, P-2781-901 Oeiras, Portugal |
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Abstract: | Clonal interference (CI) is a phenomenon that may be important in several asexual microbes. It occurs when population sizes are large and mutation rates to new beneficial alleles are of significant magnitude. Here we explore the role of gene flow and spatial heterogeneity in selection strength in the adaptation of asexuals. We consider a subdivided population of individuals that are adapting, through new beneficial mutations, and that migrate between different patches. The fitness effect of each mutation depends on the patch and all mutations considered are assumed to be unconditionally beneficial. We find that spatial variation in selection pressure affects the rate of adaptive evolution and its qualitative effects depend on the level of gene flow. In particular, we find that both low migration and high levels of heterogeneity lead to enhanced CI. In contrast, for high levels of migration the rate of fixation of adaptive mutations is higher when environmental heterogeneity is present. In addition, we observe that the level of fitness variation is higher and simultaneous fixation of multiple mutations tends to occur in the regime of low migration rates and high heterogeneity. |
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Keywords: | Adaptation gene flow mutations population genetics population structure |
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