Intron loss partially affects fitness and thus is under weak negative selection.
First, we show that single nucleotide polymorphisms in disordered regions are under weaker negative selection compared with more structured protein regions and have a higher proportion of neutral non-synonymous sites.
Furthermore, indels in disordered regions are under weaker negative selection relative to structured protein regions, and a large degree of variation in protein length is attributable to disordered regions (Light, Sagit, Sachenkova, et al. 2013).
The LRTs from the branch models analysis indicate that clade L, but not clade G (Figs. 2, 3 and 4), is under weaker negative selection, as ωL was significantly different between clade L and the background level (Table 2).> A site model analysis allows the ω ratio to vary among sites (among codons or amino acids).
The dN/dS ratio of 0.64 in non-aligned regions suggests that these sequences are under very weak negative selective pressure, with purifying selection perhaps acting only to maintain non-globular structure.
Our investigation suggests that amino acid polymorphisms in disordered regions of both humans and yeast are under slightly weaker negative selection compared with structured protein regions.
In those families (42 families) which are under nearly no restriction by disulfide bonds, there is a weak negative correlation between SSS and SIDS among different families (r = −0.46, p<0.01).
There were also weak negative phenotypic correlations between these two traits under both SPF and non-SPF conditions.
The DI had a weak positive correlation with the pollutants, except with O3 where there was a weak negative correlation.
If we use dN/dS as an estimate of selective pressure and dS as an estimate of time, we can state that older paralogs are evolving under stronger negative selection, while younger paralogs often evolve under weaker negative selection, and sometimes even with dN/dS > 1.
