The fate of balanced, phenotypic polymorphisms in fragmented metapopulations

Craze, Paul G.

doi:10.1111/j.1420-9101.2009.01764.x

Cited by 7 publications

(6 citation statements)

References 31 publications

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“…However, we did not find this geographic variation to be related to factors that may influence populations structure (i.e., density and vegetation characteristics), nor is there a clear geographic pattern to it. Therefore, our results do not support the hypothesis [6] that deviation from 50:50 proportions is due to genetic drift.…”

Section: Resultscontrasting

confidence: 99%

Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

Looijestijn¹,

Chua²,

Aguirre‐Gutiérrez

et al. 2014

Preprint

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One of the very few snail taxa that display genetic antisymmetry (that is, roughly even mixes of genetically determined clockwise and anticlockwise individuals within a single population) are the circa 35 species of the tropical tree snail subgenus Amphidromus. Previous work has shown that this may be due to a particular type of sexual selection, in which sperm transfer is improved in copulations between the two mirror-image morphs. However, it is not yet clear why so often significant deviations from 50:50 proportions are found. Modelling studies show that population structure will affect the degree by which the dimorphism is skewed towards the morph associated with the recessive allele. In this study, we mapped the proportions of sinistrals (PropS) in 56 demes in A. inversus on the Malaysian island of Kapas. We also mapped population density, predation rates, and several measures of vegetation structure. Our results show that PropS amounts on average to 0.65, but across the island varies from 0.30 to 0.85. Density and overall predation are inversely correlated, but neither predicts PropS. Vegetation parameters also do not correlate with the proportion of sinistrals. We do, however, find a negative correlation between the predation rate on sinistrals and PropS, a finding which may warrant further study.

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Section: Resultscontrasting

confidence: 99%

Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

Looijestijn¹,

Chua²,

Aguirre‐Gutiérrez

et al. 2014

Preprint

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“…We assume a fitness function for negative frequency‐dependent viability selection, w i = f ( P i ), as a decreasing function of the frequency of phenotype P i ( i = 1, 3), P i . We use a linear NFDS function, f ( P i ) = 1 – sP i , where s is a positive constant (Craze ) and conduct diffusion approximation analyses in finite populations (Appendix S4). When selection is weak, this linear NFDS model is equivalent to the disassortative mating model of Yamamichi and Sasaki () (note that mating in the model of Yamamichi and Sasaki is assortative when the parameter r is positive, but is disassortative when r is negative).…”

Section: Modelsmentioning

confidence: 99%

Roles of maternal effects in maintaining genetic variation: Maternal storage effect

Yamamichi

Hoso

2016

Evolution

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Understanding the maintenance of genetic variation remains a central challenge in evolutionary biology. Recent empirical studies suggest the importance of temporally varying selection, as allele frequencies have been found to fluctuate substantially in the wild. However, previous theory suggests that the conditions for the maintenance of genetic variation under temporally fluctuating selection are quite restrictive. Using mathematical models, we demonstrate that maternal genetic effects, whereby maternal genotypes affect offspring phenotypes, can facilitate the maintenance of polymorphism in temporally varying environments. Maternal effects result in mismatches between genotypes and phenotypes, thereby buffering the influence of selection on allele frequency. This decreases the magnitude of allele-frequency fluctuations and creates conditions for the maintenance of variation when selection causes fluctuations. Therefore, maternal effects may result in a temporal storage effect ("maternal storage effect"). On the other hand, when selection does not cause fluctuations (e.g., linear negative frequency-dependent selection), maternal genetic effects moderate the relative importance of selection compared to genetic drift and promote stochastic allele extinction in finite populations. Thus, maternal effects can play an important role in the maintenance of polymorphism, but the direction of the effect depends on the nature of selection.

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“…They found that the equilibrium frequency of these mutations and the resulting phenotypes depended on whether they were recessive or dominant, with dominant sterility mutations more likely to be maintained globally when rare, implying an effect of Haldane's Sieve. Finally, Craze () presented a computational model of these effects for polymorphisms maintained by frequency‐dependent selection in metapopulations generally, although with a focus on the effects of local drift, as in Barrett et al . ().…”

Section: Discussionmentioning

confidence: 99%

The opposing effects of genetic drift and Haldane's sieve on floral‐morph frequencies in tristylous metapopulations

Roux

Pannell

2019

New Phytologist

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Summary Tristyly is a genetic floral polymorphism in which three floral morphs are maintained at equal frequencies by negative frequency‐dependent selection on alleles at two interacting loci. Because dominant alleles at these loci are maintained at a lower frequency than their recessive counterparts, they are more likely to be lost by founder events and genetic drift.Here we examine the hypothesis that dominant alleles under negative frequency‐dependent selection should also be more likely to re‐invade populations than recessive alleles, due to Haldane's Sieve, because recessive alleles not expressed in a heterozygote state cannot benefit from positive selection when rare.We used computer simulations of tristylous metapopulations to verify that Haldane's Sieve acting on migrants into occupied demes can indeed reverse the bias in allele frequencies expected for small single tristylous populations, particularly in situations of rapid population growth following colonisation. This effect is manifest both locally and at the metapopulation level.Our study illustrates the potential effect of Haldane's Sieve in the novel context of an iconic plant sexual‐system polymorphism under the influence of metapopulation dynamics.

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The fate of balanced, phenotypic polymorphisms in fragmented metapopulations

Cited by 7 publications

References 31 publications

Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

Mapping of dextral : sinistral proportions in the chirally dimorphic land snail Amphidromus inversus

Roles of maternal effects in maintaining genetic variation: Maternal storage effect

The opposing effects of genetic drift and Haldane's sieve on floral‐morph frequencies in tristylous metapopulations

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