directional selection


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Related to directional selection: Stabilizing selection

directional selection

the SELECTION of a character in one direction, e.g. towards larger size, that may occur as a result in a change in environment. For example, if another ice age was imminent then temperature would fall and the overall size of warm-blooded vertebrates living in a particular region would probably increase. See BERGMANN'S RULE.
References in periodicals archive ?
The magnitude of directional selection ([beta]) on life history traits detected in this study (range 0.
The analysis of standardized selection differentials revealed only directional selection on tibia length favoring females (Fig.
While feeding structures typically are subject to stabilizing selection, favoring optimal cost-effectiveness, structures used in antipredator defense are subject to directional selection, favoring maximum affordable effect (cf.
Unlike least squares regression, this procedure may only reveal directional selection, but says nothing regarding nonlinear selection (Price and Boag 1987).
Moreover, this correlated response was not simply due to genetic drift acting alone, because the linear trend suggested that directional selection was an important factor.
where [Gamma] is the matrix of nonlinear selection coefficients and [Beta] is the vector of directional selection gradients and the superscript T denotes matrix transposition (eq.
Comparisons of directional selection coefficient between HL and FP populations planted in their native sites revealed a significant difference for only one trait.
However, the two genes, Tas2r49 and Tas2r3, were associated with bitter taste and were under directional selection between the QIN and non-QIN populations, showing no signal of directional selection between MIN and QXL populations.
Predicting microevolutionary responses to directional selection on heritable variation.
2] is not a lethal selection agent, nor results in strong directional selection.
Correct experimental designs to estimate heritability for continuous and threshold traits from a directional selection experiment are given, as well as appropriate standard errors of the estimates, properly accounting for sampling variance and variance from drift.
Because such traits signal one's overall fitness, they tend to become exaggerated through evolution, in a process called directional selection.

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