Different mechanisms drive the maintenance of polymorphism at loci subject to strong versus weak fluctuating selection
AffiliationUniv Arizona, Dept Ecol & Evolutionary Biol
MetadataShow full item record
CitationBertram, J. and Masel, J. (2019), Different mechanisms drive the maintenance of polymorphism at loci subject to strong versus weak fluctuating selection. Evolution, 73: 883-896. doi:10.1111/evo.13719
Rights© 2019 The Author(s). Evolution © 2019 The Society for the Study of Evolution.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractThe long-running debate about the role of selection in maintaining genetic variation has been given new impetus by the discovery of hundreds of seasonally oscillating polymorphisms in wild Drosophila, possibly stabilized by an alternating summer-winter selection regime. Historically, there has been skepticism about the potential of temporal variation to balance polymorphism, because selection must be strong to have a meaningful stabilizing effect-unless dominance also varies over time ("reversal of dominance"). Here, we develop a simplified model of seasonally variable selection that simultaneously incorporates four different stabilizing mechanisms, including two genetic mechanisms ("cumulative overdominance" and reversal of dominance), as well as ecological "storage" ("protection from selection" and boom-bust demography). We use our model to compare the stabilizing effects of these mechanisms. Although reversal of dominance has by far the greatest stabilizing effect, we argue that the three other mechanisms could also stabilize polymorphism under plausible conditions, particularly when all three are present. With many loci subject to diminishing returns epistasis, reversal of dominance stabilizes many alleles of small effect. This makes the combination of the other three mechanisms, which are incapable of stabilizing small effect alleles, a better candidate for stabilizing the detectable frequency oscillations of large effect alleles.
Note12 month embargo; published online: 18 March 2019
VersionFinal accepted manuscript
SponsorsJohn Templeton Foundation 
- Seasonally fluctuating selection can maintain polymorphism at many loci via segregation lift.
- Authors: Wittmann MJ, Bergland AO, Feldman MW, Schmidt PS, Petrov DA
- Issue date: 2017 Nov 14
- Multilocus selection in subdivided populations II. Maintenance of polymorphism under weak or strong migration.
- Authors: Bürger R
- Issue date: 2009 Jun
- Pleiotropic models of polygenic variation, stabilizing selection, and epistasis.
- Authors: Gavrilets S, de Jong G
- Issue date: 1993 Jun
- Genomic evidence of rapid and stable adaptive oscillations over seasonal time scales in Drosophila.
- Authors: Bergland AO, Behrman EL, O'Brien KR, Schmidt PS, Petrov DA
- Issue date: 2014 Nov
- A reanalysis of protein polymorphism in Drosophila melanogaster, D. simulans, D. sechellia and D. mauritiana: effects of population size and selection.
- Authors: Morton RA, Choudhary M, Cariou ML, Singh RS
- Issue date: 2004 Mar