Selection: There are two distinct but somewhat related definitions for this term:

In model organism research, a selection is a process through which a researcher is attempting to find rare individuals with certain phenotypesplugin-autotooltip__default plugin-autotooltip_bigPhenotype: an observable feature or property of an organism. and has some way of enriching for the rare individuals by killing off all other individuals that do not match the search criteria. Contrast to a screenplugin-autotooltip__default plugin-autotooltip_bigScreen: a screen is a process through which a researcher looks through a population of individuals in an attempt to find rare individuals with certain phenotypes, usually with no obvious way to enrich for the rare individuals. contrast to a selection..

In population genetics, selection refers the environment conferring an advantage in survival or reproduction to individuals of one genotypeplugin-autotooltip__default plugin-autotooltip_bigGenotype: the combination of alleles within an organism or strain. When used as a verb, it means to determine the genotype experimentally. over another.