population genetics

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The branch of science that deals with the statistical analysis of the inheritance and prevalence of genes in populations and genetic divergence between populations.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The study of the allele frequency distribution and change under the influence of the four evolutionary processes: natural selection, genetic drift, mutation and gene flow.