Genetic Strategy Diallele Crosses Selection QTL Maps RI F2 Random Mutants Targeted Mutants Source of variation Existing Existing Existing + + New random induced New targeted No. genes Multigenic Multigenic Multigenic + + Single gene Single Type of output Heritability (h2) (h2) (h2), Map + + Map location gene ID Phenotypic data ID of novel genes? No No Yes Yes Not relevant Advantages Quick Provides animal line Single genes + + Single genes Known genes Genotypes replicable Stable genotype + - Speedy cloning Much background information Problems No individual gene ID Lengthy Complex QTL to gene Many genes missed No novel genes Question addressed Is there genetic variance (VG)? Is there VG? How much VG? Can genes be found? Function: known genes How much VG? Limits of VG selection? Where are genes? What are the genes? Costs per experiment $ $$ $$$ $$$ $

Note: QTL Maps = quantitative trait loci maps.