Population genomics: Genome-wide sampling of insect populations

Modern population genetics underwent a major paradigm shift during the last decade of the 20th century with the discovery that thousands of genes of k nown function and position in a genome can be analyzed simultaneously in a single individual. The impact of this technology on insect population genet ics is potentially profound, Sampling distributions of genetic statistics c an now be derived from many individual loci or among many segregating sites within a gene. Inferences regarding random mating, gene flow, effective po pulation sizes, disequilibrium, and relatedness among populations can now b e based on patterns of variation at many loci. More importantly, genome-wid e sampling enables population geneticists to distinguish effects that act o n the whole genome from those that act on individual loci or nucleotides. W e introduce the term "population genomics" to describe the process of simul taneous sampling of numerous variable loci within a genome and the inferenc e of locus-specific effects from the sample distributions. The four critica l assumptions implicit in the population genomics approach are explained in detail. Studies adopting this paradigm are reviewed, and the steps necessa ry to complete a population genomics study are outlined.