Allele surfing promotes microbial adaptation from standing variation.
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.
Departments of Physics and Integrative Biology, University of California, Berkeley, CA, 94720, USA.
Matti
M
Gralka
Biophysics and Evolutionary Dynamics Group, Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany.
Fabian
F
Stiewe
SUPA, School of Physics and Astronomy, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ, UK.
Fred
F
Farrell
Departments of Physics and Integrative Biology, University of California, Berkeley, CA, 94720, USA.
Wolfram
W
Möbius
SUPA, School of Physics and Astronomy, The University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ, UK.|Centre for Synthetic and Systems Biology, The University of Edinburgh, Edinburgh, UK.
Bartlomiej
B
Waclaw
Departments of Physics and Integrative Biology, University of California, Berkeley, CA, 94720, USA.
Oskar
0000-0002-1312-5975
O
Hallatschek
D000222:Adaptation, Physiological / Q000235:genetics*; D000483:Alleles; D005075:Biological Evolution; D003198:Computer Simulation; D017753:Ecosystem; D008954:Models, Biological; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology*
Biological invasions; dynamics of adaptation; eco-evolutionary feedback; gene surfing; genetic drift; range expansions