title: Tests for the replication of an association between Egfr and natural variation in Drosophila melanogaster wing morphology.
abstract: BACKGROUND
  Quantitative differences between individuals stem from a combination of genetic and environmental factors, with the heritable variation being shaped by evolutionary forces. Drosophila wing shape has emerged as an attractive system for genetic dissection of multi-dimensional traits. We utilize several experimental genetic methods to validation of the contribution of several polymorphisms in the Epidermal growth factor receptor (Egfr) gene to wing shape and size, that were previously mapped in populations of Drosophila melanogaster from North Carolina (NC) and California (CA). This re-evaluation utilized different genetic testcrosses to generate heterozygous individuals with a variety of genetic backgrounds as well as sampling of new alleles from Kenyan stocks.
  
  
  RESULTS
  Only one variant, in the Egfr promoter, had replicable effects in all new experiments. However, expanded genotyping of the initial sample of inbred lines rendered the association non-significant in the CA population, while it persisted in the NC sample, suggesting population specific modification of the quantitative trait nucleotide QTN effect.
  
  
  CONCLUSIONS
  Dissection of quantitative trait variation to the nucleotide level can identify sites with replicable effects as small as one percent of the segregating genetic variation. However, the testcross approach to validate QTNs is both labor intensive and time-consuming, and is probably less useful than resampling of large independent sets of outbred individuals.
authors.affiliation: Department of Genetics, North Carolina State University, Raleigh, NC 27695, USA. apalsson@uchicago.edu
authors.forename: Arnar
authors.initials: A
authors.lastname: Palsson
authors.forename: James
authors.initials: J
authors.lastname: Dodgson
authors.forename: Ian
authors.initials: I
authors.lastname: Dworkin
authors.forename: Greg
authors.initials: G
authors.lastname: Gibson
mesh_terms: D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics*; D004331:Drosophila melanogaster / Q000235:genetics*; D066246:ErbB Receptors / Q000235:genetics*; D014644:Genetic Variation; D040582:Inheritance Patterns; D009024:Morphogenesis / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D018010:Receptors, Invertebrate Peptide / Q000235:genetics*; D014921:Wings, Animal / Q000254:growth & development*
chemical_list: D029721:Drosophila Proteins; D018010:Receptors, Invertebrate Peptide; D011494:Protein Kinases; C066532:Egfr protein, Drosophila; D066246:ErbB Receptors