Genomic evidence of rapid and stable adaptive oscillations over seasonal time scales in Drosophila.
PLoS Genet
; 10(11): e1004775, 2014 Nov.
Article
in En
| MEDLINE
| ID: mdl-25375361
ABSTRACT
In many species, genomic data have revealed pervasive adaptive evolution indicated by the fixation of beneficial alleles. However, when selection pressures are highly variable along a species' range or through time adaptive alleles may persist at intermediate frequencies for long periods. So called "balanced polymorphisms" have long been understood to be an important component of standing genetic variation, yet direct evidence of the strength of balancing selection and the stability and prevalence of balanced polymorphisms has remained elusive. We hypothesized that environmental fluctuations among seasons in a North American orchard would impose temporally variable selection on Drosophila melanogaster that would drive repeatable adaptive oscillations at balanced polymorphisms. We identified hundreds of polymorphisms whose frequency oscillates among seasons and argue that these loci are subject to strong, temporally variable selection. We show that these polymorphisms respond to acute and persistent changes in climate and are associated in predictable ways with seasonally variable phenotypes. In addition, our results suggest that adaptively oscillating polymorphisms are likely millions of years old, with some possibly predating the divergence between D. melanogaster and D. simulans. Taken together, our results are consistent with a model of balancing selection wherein rapid temporal fluctuations in climate over generational time promotes adaptive genetic diversity at loci underlying polygenic variation in fitness related phenotypes.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Polymorphism, Genetic
/
Selection, Genetic
/
Drosophila melanogaster
/
Gene-Environment Interaction
Type of study:
Prognostic_studies
/
Risk_factors_studies
Limits:
Animals
Country/Region as subject:
America do norte
Language:
En
Journal:
PLoS Genet
Journal subject:
GENETICA
Year:
2014
Document type:
Article
Affiliation country:
United States