title: Quantitative variation and gene number.
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000378:metabolism; D004331:Drosophila melanogaster; D005796:Genes; D014644:Genetic Variation; D009154:Mutation; D010641:Phenotype; D012641:Selection, Genetic; D014921:Wings, Animal / Q000033:anatomy & histology