But sometimes one of them will become fixed, and more prominent, and grow in usage over time, and that's what happened with 'squee,'" Martin said.
Dr. David L. Holmes, president of the Eden Institute, an autism center in Princeton, said, "If you have a child with autism who's not wired correctly, and we allow that to continue without intervention, those neuropathways will become fixed, and it becomes far more difficult to undo that tangled mess".
Consequently, very little is known about the details of adaptation from standing genetic variation (but see Orr and Betancourt 2001; Hermisson and Pennings 2005), that is, which of the alleles segregating in a population will become fixed and contribute to the evolutionary response.
For example, if the frequency p for allele A is 75% and the frequency q for allele B is 25%, then given unlimited time the probability A will ultimately become fixed in the population is 75% and the probability that B will become fixed is 25%.
This means that even the morph with a slightly higher potential fitness will become fixed in each population, and that one morph is fixed randomly even if the potential fitnesses of the two morphs are exactly identical.
During an episode of positive selection, advantageous substitutions will become fixed in a lineage and remain invariant in descendent lineages, elevating the ratio of RI/RV relative to the neutral expectation given by SI/SV.
Unlike static encyclopedias (i.e., encyclopedias that will become fixed in print or on CD-ROM), a dynamic encyclopedia allows entries to be updated, thereby becoming responsive to new research and advances in the field.
Is there a danger that if they describe it as one thing – the "diversity western", say, or the "anti-Trump allegory" – then it will become fixed as that forever?
But I would argue that it is impossible to protect anyone from something as significant as this: information now pervades shared existence to such an extent that the iconography of extreme violence will become fixed whatever individual decision is taken by the traditional media.
While variations in sequence and copy number for drifting genes within a family may be largely inconsequential within populations thus enabling gene loss (death), some loci will become fixed if they help acclimate the individuals to the new niches and habitats [4].
