A model of quantitative traits under frequency-dependent balancing selection

Mani, G.S.; Clarke, Bryan; Shelton, P. R.

doi:10.1098/rspb.1990.0024

Cited by 27 publications

(8 citation statements)

References 16 publications

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“…Moreover, correlational selection often results from frequency-dependent interactions such as those between predators and prey, or parasites and hosts [28]; frequency-dependence can easily result in stable polymorphisms [2] and stable quantitative variation [29]. Provided that phenotypic correlations are consistent and based upon some genetic correlation, this can favour variation in both traits.…”

Section: Discussionmentioning

confidence: 99%

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

2014

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Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and slowly. This may help explain the paradox of polymorphic aposematism: variable warning signals may reduce protection, but predator defence might still be effective if specific behaviours are tuned to specific signals. The interacting effects of behavioural and morphological traits may be a key to the evolution of warning signals.

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Section: Discussionmentioning

confidence: 99%

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

2014

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“…Phenotypic variation in threshold traits is likely to be largely a function of frequency-dependent selection or a result of phenotypic plasticity (induction of protective structures in the presence of a predator cue; Roff, 1994bRoff, , 1996. This type of selection can readily preserve phenotypic variation and can play an important role in the preservation of genetic variation in quantitative traits (Mani et al, 1990;Roff, 1997a). Its importance in maintaining genetic variation in threshold traits is explored elsewhere (Roff, 1997b).…”

Section: Discussionmentioning

confidence: 99%

Evolution of threshold traits: the balance between directional selection, drift and mutation

Roff

1998

Heredity

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Threshold traits are characterized by showing discrete phenotypes (typically two) but by being controlled by many loci of small additive effect, the expression of the phenotype being a consequence of a threshold of sensitivity. In the case of a dimorphic threshold trait, individuals above the threshold display one morph and individuals below the threshold display the alternate. Many threshold traits, such as sex ratio, cyclomorphosis, paedomorphosis and wing dimorphism, are closely connected to fitness but have high heritabilities. The present study investigates the hypothesis that these large heritabilities can be maintained even in the face of directional selection by the countervailing force of mutation. This hypothesis is based on the observation that as selection proceeds to shift the frequency of one morph towards fixation, the selection intensity necessarily declines permitting mutation to restore genetic variation. The hypothesis is tested using a simulation model and a theoretical analysis, the latter assuming no genetic drift. It is shown that over 80 per cent of the original genetic variance can be maintained at equilibrium provided the population (N) and number of loci (n) are reasonably large (N 5000, n = 50). However, unless the selection coefficient is very small ( 0.001) the equilibrium frequency of the phenotypes ( 2 per cent) is considerably below that generally observed. I conclude that mutation could play a significant role in the maintenance of genetic variation in threshold traits but that some form of selection, such as frequency-dependent selection, is required to maintain the phenotypic variation.

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“…Theoretical studies have demonstrated the diversifying effects of inverse frequency-dependent selection (Mani et al 1990, Andreasen and Christiansen 1995, Cressman 1996, Hammerstein 1996. Frequency-dependent selection has been studied in predatorÐprey systems (Dale et al 1994) and in seedling dynamics of tropical trees (Augspurger and Kitajima 1992).…”

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confidence: 98%

Disruptive Selection Maintains Variable Pheromone Blends in the Bark Beetle Ips pini

et al. 2011

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The presence of heritable variation is a prerequisite for evolution, but natural selection typically reduces genetic variation. Variation can be maintained in traits under selection through spatial or temporal variation in fitness surfaces, frequency-dependent selection, or disruptive selection. We evaluated the maintenance of variation in the enantiomeric blend of pheromones employed by the bark beetle Ips pini (Say). In natural populations, we quantified fitness surfaces for mating success and progeny production. We investigated the effects of paternal pheromone blend on offspring survival by comparing the spatial scales at which pheromone blends and larval mortality agents vary. Males with extreme pheromone blends obtained up to 1.8 times as many mates who each laid equivalent numbers of eggs, producing strong disruptive selection on male pheromone blend. In combination with imperfect assortative mating that continually produces intermediate genotypes, this fitness surface is sufficient to maintain variation in a heritable trait that is strongly linked to fitness. The ultimate explanation for female preference is unknown but could be because of selection for reduced mortality from specialist predators that prefer common prey pheromone blends. Selection is most likely occurring at the scale of small resource patches within pine stands. Selection at coarser scales (pine stands) is unlikely because pheromone blends did not vary among pine stands. Selection at finer scales (within logs) is unlikely because males of similar enantiomeric blends were not aggregated on logs, and male pheromone blend did not affect the spacing to neighboring galleries. This study documents a rare case of diversifying selection in natural populations.

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A model of quantitative traits under frequency-dependent balancing selection

Cited by 27 publications

References 16 publications

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

Evolution of threshold traits: the balance between directional selection, drift and mutation

Disruptive Selection Maintains Variable Pheromone Blends in the Bark Beetle Ips pini

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