Plant & Animal Genomes XV Conference Plant & Animal Genomes XV ConferenceJanuary 13-17, 2007
Town & Country Convention Center
San Diego, CA
Complex traits show a continuous phenotypic distribution, and are influenced by numerous genetic and environmental factors. In contrast to Mendelian traits, which are controlled by a single genetic factor, we understand relatively little about the molecular genetic basis of variation in polygenic traits: A worrying fact given that most traits of agricultural, ecological and medical significance appear to be complex. A broad understanding of the genetic basis of complex traits would include estimates of the number and effect of the genetic polymorphisms involved, their frequencies in the natural population, the extent of genotype-by-environment interaction, and the level of epistasis. These questions can most effectively be answered by identifying the actual causative variants underlying phenotypic variation. Using the powerful model genetic system Drosophila melanogaster I am conducting a series of experiments designed to identify sites contributing to variation in bristle number, a classic quantitative trait. The information obtained from this model system can be used to aid investigation of the genetic basis of complex trait variation in other organisms. Here I will describe two approaches we use to understand the genetic basis of bristle number variation in Drosophila: High-resolution association mapping of candidate-gene regions, and a novel genome-wide mapping strategy using eight-way synthetic recombinant populations. This new approach incorporates the strengths of both QTL (quantitative trait locus) and association mapping, while eliminating some of their disadvantages, and may prove a worthwhile alternative to traditional strategies.