For example, species exposed to selection for rapid growth tend to have more strongly selected codon usage bias.
Because deleterious mutations will be exposed to selection on the Z-chromosome when being hemizygous in females, selection, in particular selective sweeps, may therefore favour reduced variation on the Z-chromosome leading to a balanced polymorphism [ 30].
This is plausible as when robustness is very high, little variation becomes exposed to selection, and when robustness is very low, the conditionally adaptive mutations cannot accumulate because they are immediately exposed to selection.
It is also well established that many kinds of environmental and genetic perturbations can lead to the release of this accumulated genetic variation in the phenotype, by which this variation is exposed to selection and may fuel adaptation.
A major potential weakness of the PEA data used here is that it can be exposed to selection bias (Fillieule 1996; Hug and Wisler, 1998; Hocke, 2002; Hug, 2003).5 Selection bias can emerge when the selected cases (here the protest events) are not part of a random sample and do not cover the entire population.
In C. elegans, let-418 might have kept its ancient essential functions, whereas chd-3, which was not exposed to selection pressure, could have evolved towards new developmental roles.
Compared to the control populations (C1-4) where the genomes are exposed to selection in both sexes, the populations with male-limited genomes (ML1-4) showed rapid increases in male fitness, whereas the fitness of females expressing ML-evolved chromosomes decreased [1].
Available studies are scarce, and are exposed to selection bias.
Once nongenic ORFs get transcribed and translated, they are considered protogenes, which are exposed to selection.
For example, recessive mutations are exposed to selection in the hemizygous X of males.
Non-randomized phase II trials are exposed to selection biases related to the respective eligibility criteria.
