Selection for an Invariant Character—‘Vibrissa Number’—in the House Mouse

Dun, RB; Fraser, AS

doi:10.1038/1811018a0

Cited by 86 publications

(72 citation statements)

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“…Measurements of the morphology of other cortical areas as well as observations of other potentially related phenotypes such as peripheral innervation (Dun and Fraser 1958;Welker and Van der Loos 1986) and forepaw size (Margret et al 2003) will allow facilitate analyses that address the nature of the specific network of QTL relationships, however. Collection of related phenotypic data in a reference population allows researchers to build associative and (through the directional relationships between locus and trait implicit in QTL analyses) causal networks between potentially related phenotypes and to test hypotheses about the nature of the relationship between QTL and phenotype.…”

Section: Dissecting the Architecture Of Related Traitsmentioning

confidence: 99%

Genetic analysis of barrel field size in the first somatosensory area (SI) in inbred and recombinant inbred strains of mice

Xin

et al. 2005

Somatosensory & Motor Research

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We measured the combined area of posterior medial barrel subfield (PMBSF) and anterior lateral barrel subfield (ALBSF) areas in four common inbred strains (C3H/HeJ, A /J, C57BL /6J, DBA/2J), B6D2F1, and ten recombinant inbred (RI) strains generated from C57BL/6J and DBA/2J progenitors (BXD) as an initial attempt to examine the genetic influences underlying natural variation in barrel field size in adult mice. These two subfields are associated with the representation of the whisker pad and sinus hairs on the contralateral face. Using cytochrome oxidase labeling to visualize the barrel field, we measured the size of the combined subfields in each mouse strain. We also measured body weight and brain weight in each strain. We report that DBA/2J mice have a larger combined PMBSF/ALBSF area (6.15 +/- 0.10 mm(2), n = 7) than C57BL /6J (5.48 +/- 0.13 mm(2), n = 10), C3H/HeJ (5.37 +/- 0.16 mm(2), n = 10), and A/J mice (5.04 +/- 0.09 mm(2), n = 15), despite the fact that DBA/2J mice have smaller average brain and body sizes. This finding may reflect dissociation between systems that control brain size with those that regulate barrel field area. In addition, BXD strains (average n = 4) and parental strains showed considerable and continuous variation in PMBSF/ALBSF area, suggesting that this trait is polygenic. Furthermore, brain, body, and cortex weights have heritable differences between inbred strains and among BXD strains. PMBSF/ALBSF pattern appears similar among inbred and BXD strains, suggesting that somatosensory patterning reflects a common plan of organization. This data is an important first step in the quantitative genetic analysis of the parcellation of neocortex into diverse cytoarchitectonic zones that vary widely within and between species, and in identifying the genetic factors underlying barrel field size using quantitative trait locus (QTL) analyses.

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Section: Dissecting the Architecture Of Related Traitsmentioning

confidence: 99%

Genetic analysis of barrel field size in the first somatosensory area (SI) in inbred and recombinant inbred strains of mice

Xin

et al. 2005

Somatosensory & Motor Research

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“…In mutants of the sex-linked gene Tabby, the number of whiskers is substantially reduced and varies considerably. That this variation has a genetic component is shown by the effectiveness of directional selection on the number of whiskers (Rendel 1979;Dun and Fraser 1958). A second, analogous example concerns changes in the number of scutellar bristles caused by the mutant scute of Drosophila melanogaster (Rendel 1979).…”

Section: Epigenetic Stability and The Evolution Of Developmentalmentioning

confidence: 99%

Does Evolutionary Plasticity Evolve?

Wagner¹

1996

Evolution

214

252

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During the development of a multicellular organism from a zygote, a large number of epigenetic interactions take place on every level of suborganismal organization. This raises the possibility that the system of epigenetic interactions may compensate or "buffer" some of the changes that occur as mutations on its lowest levels, and thus stabilize the phenotype with respect to mutations. This hypothetical phenomenon will be called "epigenetic stability." Its potential importance stems from the fact that phenotypic variation with a genetic basis is an essential prerequisite for evolution. Thus, variation in epigenetic stability might profoundly affect attainable rates of evolution. While representing a systemic property of a developmental system, epigenetic stability might itself be genetically determined and thus be subject to evolutionary change. Whether or not this is the case should ideally be answered directly, that is, by experimentation. The time scale involved and our insufficient quantitative understanding of developmental pathways will probably preclude such an approach in the foreseeable future. Preliminary answers are sought here by using a biochemically motivated model of a small but central part of a developmental pathway. Modeled are sets of transcriptional regulators that mutually regulate each other's expression and thereby form stable gene expression patterns. Such gene-expression patterns, crucially involved in determining developmental pattern formation events, are most likely subject to strong stabilizing natural selection. After long periods of stabilizing selection, the fraction of mutations causing changes in gene-expression patterns is substantially reduced in the model. Epigenetic stability has increased. This phenomenon is found for widely varying regulatory scenarios among transcription factor genes. It is discussed that only epistatic (nonlinear) gene interactions can cause such change in epigenetic stability. Evidence from paleontology, molecular evolution, development, and genetics, consistent with the existence of variation in epigenetic stability, is discussed. The relation of epigenetic stability to developmental canalization is outlined. Experimental scenarios are suggested that may provide further evidence.

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“…One example is the effect of the sex-linked Tabby mutation on whisker number in mice (Dunn and Fraser 1958). Almost all mice have 19 secondary vibrissae on each side of the snout, with little variation, but on the genetic background of the Tabby mutation, the mean is reduced to 12 and the range is eight to 16 whiskers, a dramatic increase in the phenotypic variance.…”

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confidence: 99%

Evolution of the Environmental Component of the Phenotypic Variance: Stabilizing Selection in Changing Environments and the Cost of Homogeneity

Zhang

Hill

2005

Evolution

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Quantitative traits show abundant genetic, environmental, and phenotypic variance, yet if they are subject to stabilizing selection for an optimal phenotype, both the genetic and environmental components are expected to decline. The mechanisms that determine the level and maintenance of phenotypic variance are not yet fully understood. While there has been extensive study of mechanisms maintaining genetic variability, it has generally been assumed that environmental variance is not dependent on the genotype and therefore not subject to change. However, accumulating data suggest that the environmental variance is under some degree of genetic control. In this study, it is assumed accordingly that both the genotypic value (i.e., mean phenotypic value) and the variance of phenotypic value given genotypic value depend on the genotype. Two models are investigated as potentially able to explain the protected maintenance of environmental variance of quantitative traits under stabilizing selection. One is varying environment among generations, such that both the optimal phenotype and the strength of the stabilizing selection vary between generations. The other is the cost of homogeneity, which is based on an assumption of an engineering cost of minimizing variability in development. It is shown that a small homogeneity cost is enough to maintain the observed levels of environmental variance, whereas a large amount of temporal variation in the optimal phenotype and the strength of selection would be necessary.

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Selection for an Invariant Character—‘Vibrissa Number’—in the House Mouse

Cited by 86 publications

References 0 publications

Genetic analysis of barrel field size in the first somatosensory area (SI) in inbred and recombinant inbred strains of mice

Genetic analysis of barrel field size in the first somatosensory area (SI) in inbred and recombinant inbred strains of mice

Does Evolutionary Plasticity Evolve?

Evolution of the Environmental Component of the Phenotypic Variance: Stabilizing Selection in Changing Environments and the Cost of Homogeneity

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