PT  - JOURNAL ARTICLE
AU  - Matti Gralka
AU  - Fabian Stiewe
AU  - Fred Farrell
AU  - Wolfram Möebius
AU  - Bartek Waclaw
AU  - Oskar Hallatschek
TI  - Allele Surfing Promotes Microbial Adaptation from Standing Variation
AID  - 10.1101/049353
DP  - 2016 Jan 01
TA  - bioRxiv
PG  - 049353
4099  - http://biorxiv.org/content/early/2016/04/19/049353.short
4100  - http://biorxiv.org/content/early/2016/04/19/049353.full
AB  - The coupling of ecology and evolution during range expansions enables mutations to establish at expanding range margins and reach high frequencies. This phenomenon, called allele surfing, is thought to have caused revolutions in the gene pool of many species, most evidently in microbial communities. It has remained unclear, however, under which conditions allele surfing promotes or hinders adaptation. Here, using microbial experiments and simulations, we show that, starting with standing adaptive variation, range expansions generate a larger increase in mean fitness than spatially uniform population expansions. The adaptation gain results from ‘soft’ selective sweeps emerging from surfing beneficial mutations. The rate of these surfing events is shown to sensitively depend on the strength of genetic drift, which varies among strains and environmental conditions. More generally, allele surfing promotes the rate of adaptation per biomass produced, which could help developing biofilms and other resource-limited populations to cope with environmental challenges.