Selection at Linked Sites Shapes Heritable Phenotypic Variation in C. elegans

Abstract

Selection and Variation In order to understand adaptation and evolution, it is necessary to understand the relationship between natural phenotypic variation and population genetics. Rockman et al. (p. 372 ; see the Perspective by Charlesworth ) examined the level of genetic variance affecting gene expression through the comparison of two strains of the nematode Caenorhabditis elegans . Surprisingly, the variation observed in each trait was better explained by the genomic pattern of background selection than by selection on the traits themselves. Thus, the removal of deleterious mutations from the population by selection reduces phenotypic variability caused by genetic variation at closely linked neutral or nearly neutral sites, and quantitative variability in gene expression shows a similar pattern to sequence diversity and is affected by local rates of genetic recombination and the effective population size.