This 'evolutionary potential' ρ c represents the relative probability for additions/deletions of domains of category c to be fixed in the population by selection and is predicted to equal the scaling exponent α c.
There are three general ways duplicated genes can be fixed in a population by selection: (1) 'dosage selection', beneficial increase in dosage due to multiple copies, (2) 'subfunctionalization', specialization of previously existing functions, or (3) 'neofunctionalization', creation of a novel function through the accumulation of beneficial, gain-of-function mutations (Ohno, 1970).
Also, rearrangements may tend to occur or to be fixed in regions of relaxed purifying selection and, thus, of faster genic evolution [ 5, 36].
That is, if the same random mutation occurs in each population or species independently by chance, it could be fixed in all due to the similar selection pressure.
When fitness is assumed to be constant, only those mutations with higher fitness values will be fixed in a haploid population under strong selection and negligible random drift.
By contrast, when one allele confers a much higher fitness that all others, this allele will likely be fixed in the population, and strong negative selection will prevent the spread of alternative alleles.
Once foreign genes are passed onto offspring, they can be fixed in the population through drift or positive selection on newly acquired functions.
In the calculation of LD between significant SNPs, two of the significant SNPs were fixed in C5, an indication of selection at those loci.
If these two populations are geographically or ecologically isolated, it is possible that A0 mutates to A1 in population 1 and this mutant allele is fixed in the population by natural selection or genetic drift.
One interesting result is that, for both AHR1 and AHR2, neither specific haplotypes nor the SNPs exhibiting evidence for selection were fixed in DLC-resistant fish populations, raising questions about their contribution to the resistant phenotype.
