2003/04/01 by H. Allen Orr · 8 citations
Biochemistry, Genetics and Molecular Biology · Social Sciences · #Evolution and Genetic Dynamics #Genetic diversity and population structure #Evolutionary Game Theory and Cooperation
paper · pdf · doi:10.1093/genetics/163.4.1519
openalex publication_date 2003/04/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We know little about the distribution of fitness effects among new beneficial mutations, a problem that partly reflects the rarity of these changes. Surprisingly, though, population genetic theory allows us to predict what this distribution should look like under fairly general assumptions. Using extreme value theory, I derive this distribution and show that it has two unexpected properties. First, the distribution of beneficial fitness effects at a gene is exponential. Second, the distribution of beneficial effects at a gene has the same mean regardless of the fitness of the present wild-type allele. Adaptation from new mutations is thus characterized by a kind of invariance: natural selection chooses from the same spectrum of beneficial effects at a locus independent of the fitness rank of the present wild type. I show that these findings are reasonably robust to deviations from several assumptions. I further show that one can back calculate the mean size of new beneficial mutations from the observed mean size of fixed beneficial mutations.