Darwin to DNA, molecules to morphology: the end of classical population genetics and the road ahead.

Molecular reductionism has permeated all of biology and because of successive new technical breakthroughs it has succeeded in unraveling the structural details of genes and genomes. The molecular revolution has reached its reductionist limit, i.e., the study of component parts in isolation, and is ready to come full circle through genomics, proteomics, and gene expression studies back to the phenotype and bring evolutionary biology to confront the Darwinian paradigm, the relationship between gene, organism, and environment. Classical experimental population genetics, dealing with genetic polymorphism and estimation of selection coefficients on a gene-by-gene basis, is coming to an end and a new era of interdisciplinary and interactive biology focusing on dynamic relationships among gene, organism, and environment has begun. In the new population genetics, there will be a shift in focus from single genes to gene networks, from gene-structure to gene-regulation, from additivity to epistasis, and from simple phenotypes to gene-interaction networks and the evolution of complex and modular systems.