Quantitative trait loci in Drosophila

• Published in: Nature reviews. Genetics Vol. 2; no. 1; pp. 11 - 20
• Main Author: Mackay, Trudy F. C
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2001; Nature Publishing Group
• Subjects: Agriculture; Animal Genetics and Genomics; Animals; Biomedical and Life Sciences; Biomedicine; Cancer Research; Chromosome Mapping; Drosophila melanogaster - genetics; Female; Gene Function; Genes; Genetic engineering; Genomics; Genotype & phenotype; Human Genetics; Humans; Insects; Linkage Disequilibrium; Male; Mutagenesis; Mutation; Norms; Pharmaceutical industry; Quantitative genetics; Quantitative Trait, Heritable; review-article; North Carolina; United States > US
• ISSN: 1471-0056; 1471-0064
• DOI: 10.1038/35047544

Key Points Quantitative trait phenotypes are continuously distributed in natural populations, due to segregation of alleles at multiple quantitative trait loci (QTL) and environmental sensitivity of QTL alleles. Determining the genetic and environmental bases of variation for quantitative traits is important for human health, agriculture, and the study of evolution. Complete genetic dissection of quantitative traits is currently feasible only in genetically tractable and well characterized model systems, such as Drosophila melanogaster . Genomic regions containing QTL affecting within-species variation (in sensory bristle number, wing shape, life span and other life history traits) and variation in morphological differences between species have been mapped by linkage to neutral, polymorphic molecular markers. Multiple QTL affect variation in each of the traits studied. Drosophila QTL often have sex- and/or environment-specific effects, and can interact non-additively (that is, exhibit epistasis). Drosophila QTL are mapped with high resolution using a quantitative version of deficiency complementation mapping. Genetic loci that interact with QTL alleles are identified using quantitative complementation tests, provided stocks with mutant alleles exist. Screens for viable P transposable element-induced mutations with quantitative phenotypic effects define novel pleiotropic effects of known loci and functions of predicted genes, and provide mutant stocks that can be used in quantitative complementation tests. Linkage disequilibrium mapping is used to determine which candidate genes correspond to QTL, and which molecular polymorphisms within candidate genes are associated with quantitative variation in phenotypes. Molecular polymorphisms in non-coding regions of candidate genes are associated with quantitative variation in phenotypes; such associations are often sex-specific. Quantitative traits in other organisms are likely to have equally complex genetic architectures. Phenotypic variation for quantitative traits results from the simultaneous segregation of alleles at multiple quantitative trait loci. Understanding the genetic architecture of quantitative traits begins with mapping quantitative trait loci to broad genomic regions and ends with the molecular definition of quantitative trait loci alleles. This has been accomplished for some quantitative trait loci in Drosophila . Drosophila quantitative trait loci have sex-, environment- and genotype-specific effects, and are often associated with molecular polymorphisms in non-coding regions of candidate genes. These observations offer valuable lessons to those seeking to understand quantitative traits in other organisms, including humans.