Drosophila bristles and the nature of quantitative genetic variation

Philos Trans R Soc Lond B Biol Sci. 2005 Jul 29;360(1459):1513-27. doi: 10.1098/rstb.2005.1672.


Numbers of Drosophila sensory bristles present an ideal model system to elucidate the genetic basis of variation for quantitative traits. Here, we review recent evidence that the genetic architecture of variation for bristle numbers is surprisingly complex. A substantial fraction of the Drosophila genome affects bristle number, indicating pervasive pleiotropy of genes that affect quantitative traits. Further, a large number of loci, often with sex- and environment-specific effects that are also conditional on background genotype, affect natural variation in bristle number. Despite this complexity, an understanding of the molecular basis of natural variation in bristle number is emerging from linkage disequilibrium mapping studies of individual candidate genes that affect the development of sensory bristles. We show that there is naturally segregating genetic variance for environmental plasticity of abdominal and sternopleural bristle number. For abdominal bristle number this variance can be attributed in part to an abnormal abdomen-like phenotype that resembles the phenotype of mutants defective in catecholamine biosynthesis. Dopa decarboxylase (Ddc) encodes the enzyme that catalyses the final step in the synthesis of dopamine, a major Drosophila catecholamine and neurotransmitter. We found that molecular polymorphisms at Ddc are indeed associated with variation in environmental plasticity of abdominal bristle number.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Dopa Decarboxylase / genetics
  • Drosophila / anatomy & histology*
  • Drosophila / genetics*
  • Drosophila Proteins / genetics
  • Environment*
  • Epistasis, Genetic*
  • Genetic Variation*
  • Genotype
  • Heterozygote
  • Linkage Disequilibrium
  • Mutation / genetics
  • Nuclear Proteins / genetics
  • Phenotype*
  • Quantitative Trait, Heritable*
  • RNA-Binding Proteins / genetics
  • Sex Factors


  • Drosophila Proteins
  • Nuclear Proteins
  • PSI protein, Drosophila
  • RNA-Binding Proteins
  • Dopa Decarboxylase