directional selection

(redirected from Positive 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 ?
In humans, the need to escape preexisting immunity exerts positive selection pressure on changes in amino acids comprising the antigenic sites of the surface glycoproteins, HA and neuraminidase (NA) (6,10).
Expected defaults modestly reduced to reflect signs of positive selection among remaining borrowers 'current' on their mortgage payments;
We calculated a standardized integrated extended haplotype homozygsity (iES(z)) value to identify significant regions of positive selection (p = 0.
So we can now consider the positive selection possibility unlikely," he added.
Similar alterations have been related to positive selection affecting other ENV as EV30 (12), determining its evolution over the time.
While there has been positive selection in the collateral attributes of the remaining performing borrowers as the highest-risk borrowers drop out of the picture, the increased market stress is outweighing any benefit from the positive selection,' said Bailey.
The resistant allele of the Mx gene could be subject to positive selection (Jansa et al.
Fitch does, however, recognize that while the elimination of extensions has increased default rates, it also increases the positive selection of the pools by allowing the weaker borrowers to be removed.
for the use and application of Genome BioSciences' patent pending Positive - Positive Selection gene targeting technology.
As opposed to conventional systems which use positive selection of stem and progenitor cells, the HDM technology depletes the unwanted cells, through use of specific antibodies targeted against the undesirable cells, thus preserving the spectrum of cells required for facilitating blood and immune system reconstitution.
Food and Drug Administration (FDA) later this year for an upgrade package to enhance the performance of the positive selection Isolex(R) 300i instrument now being sold in the United States.