Alternative phenotypes and sexual selection: can dichotomous handicaps honestly signal quality?

Unrug, Juliusz; Tomkins, Joseph L.; Radwan, Jacek

doi:10.1098/rspb.2004.2729

Cited by 35 publications

(20 citation statements)

References 44 publications

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“…A genetic correlation ought to exist between traits that are developmentally integrated (Cheverud 1996;Wagner 1996;West-Eberhard 2003;Klingenberg 2004), but we have no such evidence for O. taurus. There was no correlated response in foreleg length in O. acuminatus selected for relatively long and relatively short horns; although this study did detect correlated responses in eyes (Nijhout & Emlen 1998), because there were only two lines, the ability to detect weaker genetic correlations will have been very low (Roff 1997;Unrug et al 2004).…”

Section: Discussioncontrasting

confidence: 55%

Phenotypic plasticity in the developmental integration of morphological trade-offs and secondary sexual trait compensation

Tomkins

Kotiaho

LeBas³

2005

Proc. R. Soc. B.

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Trait exaggeration through sexual selection will take place alongside other changes in phenotype. Exaggerated morphology might be compensated by parallel changes in traits that support, enhance or facilitate exaggeration: 'secondary sexual trait compensation' (SSTC). Alternatively, exaggeration might be realized at the expense of other traits through morphological trade-offs. For the most part, SSTC has only been examined interspecifically. For these phenomena to be important intraspecifically, the sexual trait must be developmentally integrated with the compensatory or competing trait. We studied developmental integration in two species with different development: the holometabolous beetle Onthophagus taurus and the hemimetabolous earwig Forficula auricularia. Male-dimorphic variation in trait exaggeration was exploited to expose both trade-offs and SSTC. We found evidence for morphological trade-offs in O. taurus, but not F. auricularia, supporting the notion that trade-offs are more likely in closed developmental systems. However, we found these trade-offs were not limited solely to traits growing close together. Developmental integration of structures involved in SSTC were detected in both species. The developmental integration of SSTC was phenotypically plastic, such that the compensation for relatively larger sexual traits was greater in the exaggerated male morphs. Evidence of intraspecific SSTC demands studies of the selective, genetic and developmental architecture of phenotypic integration.

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Section: Discussioncontrasting

confidence: 55%

Phenotypic plasticity in the developmental integration of morphological trade-offs and secondary sexual trait compensation

Tomkins

Kotiaho

LeBas³

2005

Proc. R. Soc. B.

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“…This could give weight to the idea that there are major genes at play in our population. In Sancassania berlesei , the male dimorphism is deemed to be conditional (Unrug et al. , 2004).…”

Section: Resultsmentioning

confidence: 99%

Genetic variation underlying the expression of a polyphenism

Buzatto

Simmons

Tomkins

2012

J of Evolutionary Biology

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Polyphenic traits are widespread and represent a conditional strategy sensitive to environmental cues. The environmentally cued threshold (ET) model considers the switchpoint between alternative phenotypes as a polygenic quantitative trait with normally distributed variation. However, the genetic variation for switchpoints has rarely been explored empirically. Here, we used inbred lines to investigate the genetic variation for the switchpoint in the mite Rhizoglyphus echinopus, in which males are either fighters or scramblers. The conditionality of male dimorphism varied among inbred lines, indicating that there was genetic variation for switchpoints in the base population, as predicted by the ET model. Our results also suggest a mixture between canalized and conditional strategists in R. echinopus. We propose that major genes that canalize morph expression and affect the extent to which a trait can be conditionally expressed could be a feature of the genetic architecture of threshold traits in other taxa.

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“…The only other vertebrate for which genetic variability in a threshold trait has been documented appears to be the salamander Ambystoma talpoideum, for which Semlitsch & Wilbur (1989) reported variation in the phenotypic switch between metamorphosis and paedomorphosis in two populations. Among invertebrates, there is evidence that polyphenisms can be genetically variable in several species of insects (Moczek et al 2002 and references therein;Unrug et al 2004), suggesting that heritable differences in threshold norms of reaction may not be uncommon. Our work underscores the assertion that the theoretical and empirical constructs encompassed by threshold norms of reaction provide an appropriate framework in which to address questions pertaining to the evolutionary stability of alternative reproductive tactics (Hazel et al 1990;Hutchings & Myers 1994;Tompkins & Hazel 2007).…”

Section: Discussionmentioning

confidence: 99%

Genetic variation in threshold reaction norms for alternative reproductive tactics in male Atlantic salmon,Salmo salar

2008

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Alternative reproductive tactics may be a product of adaptive phenotypic plasticity, such that discontinuous variation in life history depends on both the genotype and the environment. Phenotypes that fall below a genetically determined threshold adopt one tactic, while those exceeding the threshold adopt the alternative tactic. We report evidence of genetic variability in maturation thresholds for male Atlantic salmon (Salmo salar) that mature either as large (more than 1 kg) anadromous males or as small (10-150 g) parr. Using a commongarden experimental protocol, we find that the growth rate at which the sneaker parr phenotype is expressed differs among pure-and mixed-population crosses. Maturation thresholds of hybrids were intermediate to those of pure crosses, consistent with the hypothesis that the life-history switch points are heritable. Our work provides evidence, for a vertebrate, that thresholds for alternative reproductive tactics differ genetically among populations and can be modelled as discontinuous reaction norms for age and size at maturity.

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Alternative phenotypes and sexual selection: can dichotomous handicaps honestly signal quality?

Cited by 35 publications

References 44 publications

Phenotypic plasticity in the developmental integration of morphological trade-offs and secondary sexual trait compensation

Phenotypic plasticity in the developmental integration of morphological trade-offs and secondary sexual trait compensation

Genetic variation underlying the expression of a polyphenism

Genetic variation in threshold reaction norms for alternative reproductive tactics in male Atlantic salmon,Salmo salar

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