Reduced selective constraint in endosymbionts: elevation in radical amino acid replacements occurs genome-wide.

ABSTRACT: As predicted by the nearly neutral model of evolution, numerous studies have shown that reduced N(e) accelerates the accumulation of slightly deleterious changes under genetic drift. While such studies have mostly focused on eukaryotes, bacteria also offer excellent models to explore the effects of N(e). Most notably, the genomes of host-dependent bacteria with small N(e) show signatures of genetic drift, including elevated K(a)/K(s). Here, I explore the utility of an alternative measure of selective constraint: the per-site rate of radical and conservative amino acid substitutions (D(r)/D(c)). I test the hypothesis that purifying selection against radical amino acid changes is less effective in two insect endosymbiont groups (Blochmannia of ants and Buchnera of aphids), compared to relate

SUBMITTER: Wernegreen JJ 

PROVIDER: S-EPMC3237559 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature