Substantial evidence of epidemiology suggests that nuclear susceptibility genes, if present, should be sustained by mutation-selection balance without heterozygote advantage.
Then, pathogenic but neutral or almost neutral genes in ancient environments could be fixed at a high frequency close to 1 by genetic drift (because the effective population size might be much smaller and the effects of genetic drift might be predominant in ancient times) and can be sustained by mutation-selection balance today.
Therefore, such genes, if sustained by mutation-selection balance, cannot be susceptibility genes but instead are PGs that decrease the risk and the severity of the disease.
Because SCZ must be sustained by mutation-selection balance without heterozygote advantage in the NGM and the mutation rates in the nuclear genome are much lower than in the mitochondrial genome [ 12- 14], the criterion is strong.
Thus we have the criterion for a susceptibility gene: (6) d < ν, where ν is defined as ν ≡ (1 − s p ) μ (1 − p ) s p.From the observation (A5), we can see that d≥ v implies s> s M for any SCZ-associated variant M which is sustained by mutation-selection balance.
Therefore, in the second stage of peripatric speciation, the genetic variability that had been sustained by frequency-dependent selection in the original large population disappears due to drift.
Redundancy in duplicate genes is difficult to sustain by natural selection (Cooke et al. 1997; Nowak et al. 1997; Wagner 2000; Qian et al. 2010), but ribosomal proteins and histones may be exceptions to this rule due to the requirement for high expression of these types of genes (Kondrashov FA and Kondrashov AS 2006; Ihmels et al. 2007; Qian et al. 2010).
In the Early families, the response was linear through 17 generations of selection and sustained by a constant input of additive genetic variance within families.
A proper process of selection, such as natural selection as it operates on genetic replicators, needs to be sustained by low rates of mutation that are simply impossible to achieve in the case of human cultural transmission.
We found selection to also occur through delayed mortality related to injuries sustained by fish that disentangle from fishing gear.
