title: Sex releases the speed limit on evolution.
abstract: Explaining the evolutionary maintenance of sex remains a key problem in evolutionary biology. One potential benefit of sex is that it may allow a more rapid adaptive response when environmental conditions change, by increasing the efficiency with which selection can fix beneficial mutations. Here I show that sex can increase the rate of adaptation in the facultatively sexual single-celled chlorophyte Chlamydomonas reinhardtii, but that the benefits of sex depend crucially on the size of the population that is adapting: sex has a marked effect in large populations but little effect in small populations. Several mechanisms have been proposed to explain the benefits of sex in a novel environment, including stochastic effects in small populations, clonal interference and epistasis between beneficial alleles. These results indicate that clonal interference is important in this system.
authors.affiliation: Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, UK. n.colegrave@ed.ac.uk
authors.forename: Nick
authors.initials: N
authors.lastname: Colegrave
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005075:Biological Evolution; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D002999:Clone Cells / Q000502:physiology; D004843:Epistasis, Genetic; D011156:Population Density; D012641:Selection, Genetic; D012723:Sex; D013269:Stochastic Processes; D013997:Time Factors