Natura non facit saltum -- Theories of adaptation: what they do and don’t say -- Testing hypotheses regarding the genetics of adaptation -- QTL mapping and the genetic basis of adaptation: recent developments -- Sex differences in recombination and mapping adaptations -- Genetics and adaptation in structured populations: sex ratio evolution in Silene vulgaris -- Studying genetics of adaptive variation in model organisms: flowering time variation in Arabidopsis lyrata -- Ontogenetics of QTL: the genetic architecture of trichome density over time in Arabidopsis thaliana -- Epistasis and genotype-environment interaction for quantitative trait loci affecting flowering time in Arabidopsis thaliana -- Evolution in heterogeneous environments and the potential of maintenance of genetic variation in traits of adaptive significance -- The genetic basis of adaptation: lessons from concealing coloration in pocket mice -- The genetics of adaptation in Drosophila sechellia -- Back to the future: genetic correlations, adaptation and speciation -- Parallel genotypic adaptation: when evolution repeats itself -- Hybridization as a source of evolutionary novelty: leaf shape in a Hawaiian composite -- Discovery and utilization of QTLs for insect resistance in soybean -- Polyploidy, evolutionary opportunity, and crop adaptation -- Quantitative trait loci and the study of plant domestication -- Can ecology help genomics: the genome as ecosystem?.An enduring controversy in evolutionary biology is the genetic basis of adaptation. Darwin emphasized "many slight differences" as the ultimate source of variation to be acted upon by natural selection. In the early 1900’s, this view was opposed by "Mendelian geneticists", who emphasized the importance of "macromutations" in evolution. The Modern Synthesis resolved this controversy, concluding that mutations in genes of very small effect were responsible for adaptive evolution. A decade ago, Allen Orr and Jerry Coyne reexamined the evidence for this neo-Darwinian view and found that both the theoretical and empirical basis for it were weak. Orr and Coyne encouraged evolutionary biologists to reexamine this neglected question: what is the genetic basis of adaptive evolution? In this volume, a new generation of biologists have taken up this challenge. Using advances in both molecular genetic and statistical techniques, evolutionary geneticists have made considerable progress in this emerging field. In this volume, a diversity of examples from plant and animal studies provides valuable information for those interested in the genetics and evolution of complex traits.