Recombination rate and protein evolution in yeast.
BACKGROUND
Theory and artificial selection experiments show that recombination can promote adaptation by enhancing the efficacy of natural selection, but the extent to which recombination affects levels of adaptation across the genome is still an open question. Because patterns of molecular evolution reflect long-term processes of mutation and selection in nature, interactions between recombination rate and genetic differentiation between species can be used to test the benefits of recombination. However, this approach faces a major difficulty: different evolutionary processes (i.e. negative versus positive selection) produce opposing relationships between recombination rate and genetic divergence, and obscure patterns predicted by individual benefits of recombination.


RESULTS
We use a combination of polymorphism and genomic data from the yeast Saccharomyces cerevisiae to infer the relative importance of nearly-neutral (i.e. slightly deleterious) evolution in different gene categories. For genes with high opportunities for slightly deleterious substitution, recombination substantially reduces the rate of molecular evolution, whereas divergence in genes with little opportunity for slightly deleterious substitution is not strongly affected by recombination.


CONCLUSIONS
These patterns indicate that adaptation throughout the genome can be strongly influenced by each gene's recombinational environment, and suggest substantial long-term fitness benefits of enhanced purifying selection associated with sexual recombination.
Department of Ecology and Evolutionary Biology,Museum of Zoology, University of Michigan, Ann Arbor, MI 48109-1079, USA. tconnal@umich.edu
Tim
T
Connallon
L Lacey
LL
Knowles
D019143:Evolution, Molecular; D014644:Genetic Variation; D016681:Genome, Fungal; D009154:Mutation; D011110:Polymorphism, Genetic; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*
D029701:Saccharomyces cerevisiae Proteins