Population genomics

Population genomics studies variation across many genomic regions in sampled biological populations. It connects genome measurements to ancestry, gene flow, demographic history and natural selection. Whereas one genetic locus gives one partly stochastic history, many loci provide repeated but potentially correlated evidence. ^[ref]

For example, comparing allele frequencies among populations can reveal broad ancestry patterns while highlighting unusually differentiated regions. Such an outlier is a candidate for explanation, not proof of local adaptation: sampling, linked variation and demographic events also affect the comparison. A sampling design must specify who was included, and reference-dependent sequencing errors can imitate biological differences if they differ systematically between groups.