Document Detail

The role of pleiotropy in the maintenance of sex in yeast.
MedLine Citation:
PMID:  17237501     Owner:  NLM     Status:  MEDLINE    
In facultatively sexual species, lineages that reproduce asexually for a period of time can accumulate mutations that reduce their ability to undergo sexual reproduction when sex is favorable. We propagated Saccharomyces cerevisiae asexually for approximately 800 generations, after which we measured the change in sexual fitness, measured as the proportion of asci observed in sporulation medium. The sporulation rate in cultures propagated asexually at small population size declined by 8%, on average, over this time period, indicating that the majority of mutations that affect sporulation rate are deleterious. Interestingly, the sporulation rate in cultures propagated asexually at large population size improved by 11%, on average, indicating that selection on asexual function effectively eliminated most of the mutations deleterious to sporulation ability. These results suggest that pleiotropy between mutations' effects on asexual fitness and sexual fitness was predominantly positive, at least for the mutations accumulated in this experimental evolution study. A positive correlation between growth rate and sporulation rate among lines also provided evidence for positive pleiotropy. These results demonstrate that, at least under certain circumstances, selection acting on asexual fitness can help to maintain sexual function.
Jessica A Hill; Sarah P Otto
Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-01-21
Journal Detail:
Title:  Genetics     Volume:  175     ISSN:  0016-6731     ISO Abbreviation:  Genetics     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-03-26     Completed Date:  2007-10-15     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0374636     Medline TA:  Genetics     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1419-27     Citation Subset:  IM    
Department of Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
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MeSH Terms
Evolution, Molecular*
Likelihood Functions
Models, Genetic*
Mutation / genetics
Population Density
Reproduction / genetics
Saccharomyces cerevisiae / genetics*,  growth & development*
Selection, Genetic*

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