Soft sweeps: molecular population genetics of adaptation from standing genetic variation.
A population can adapt to a rapid environmental change or habitat expansion in two ways. It may adapt either through new beneficial mutations that subsequently sweep through the population or by using alleles from the standing genetic variation. We use diffusion theory to calculate the probabilities for selective adaptations and find a large increase in the fixation probability for weak substitutions, if alleles originate from the standing genetic variation. We then determine the parameter regions where each scenario-standing variation vs. new mutations-is more likely. Adaptations from the standing genetic variation are favored if either the selective advantage is weak or the selection coefficient and the mutation rate are both high. Finally, we analyze the probability of "soft sweeps," where multiple copies of the selected allele contribute to a substitution, and discuss the consequences for the footprint of selection on linked neutral variation. We find that soft sweeps with weaker selective footprints are likely under both scenarios if the mutation rate and/or the selection coefficient is high.
Hermisson
Joachim
J
Section of Evolutionary Biology, Department of Biology II, Ludwig-Maximilians-University Munich, Germany. joachim.hermission@lmu.de
Pennings
Pleuni S
PS
D000222:Adaptation, Physiological; D000483:Alleles; D000818:Animals; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D006801:Humans; D008957:Models, Genetic; D015233:Models, Statistical; D008962:Models, Theoretical; D009154:Mutation; D016012:Poisson Distribution
Genetics. 2000 Jul;155(3):1415-27
10880499
Genetics. 2001 Feb;157(2):875-84
11157004
Genetics. 2002 Feb;160(2):765-77
11861577
Genetics. 2002 Mar;160(3):1179-89
11901132
Genetics. 2002 Dec;162(4):1753-61
12524346
Genetics. 2003 May;164(1):389-98
12750349
J Evol Biol. 2003 Jul;16(4):754-66
14632238
Proc Natl Acad Sci U S A. 2004 Feb 10;101(6):1626-31
14745026
Mol Ecol. 2004 Aug;13(8):2491-504
15245421
Proc Natl Acad Sci U S A. 2004 Jul 20;101(29):10667-72
15249682
Genetics. 1969 Mar;61(3):763-71
17248440
Genetics. 1992 Jan;130(1):195-204
1732160
Proc Natl Acad Sci U S A. 1991 Dec 15;88(24):11413-5
1763055
Genetics. 1989 Dec;123(4):887-99
2612899
Evolution. 1983 Nov;37(6):1210-1226
28556011
Genet Res. 1974 Feb;23(1):23-35
4407212
Genetics. 1981 Mar-Apr;97(3-4):639-66
7297851
Genetics. 1995 Jun;140(2):821-41
7498757
Genetics. 1996 Jun;143(2):621-5
8725213
Genetics. 1997 Jun;146(2):723-33
9178020