Genetic marker

Definition

A specific DNA sequence or chromosomal locus with a known location and detectable variation, used to distinguish individuals, populations, or species and to track inheritance patterns, gene flow, or evolutionary relationships. Markers include single nucleotide polymorphisms (SNPs), microsatellites, mitochondrial genes such as COI, and other variable regions that can be amplified and sequenced or genotyped.

Etymology

From Greek genetikos 'relating to origin or birth' + Old English mearc 'boundary sign'.

Example

Entomologists use the mitochondrial COI gene as a genetic marker for DNA barcoding insects, distinguishing cryptic species of parasitoid wasps that appear morphologically identical but show consistent sequence divergence.

Synonyms

• molecular marker
• DNA marker

Related Terms

• DNA barcoding
• single nucleotide polymorphism
• microsatellite
• mitochondrial DNA
• population genetics
• Phylogenetics
• genotyping
• Allele

Usage Notes

The term encompasses both the physical DNA segment and its variable state; specialists distinguish between the marker locus and the alleles or haplotypes detected. In arthropod studies, mitochondrial markers are preferred for phylogeography and species identification due to maternal inheritance and lack of recombination, while nuclear microsatellites are favored for estimating contemporary gene flow and population structure. 'Genetic marker' is broader than 'gene', as markers need not be coding regions.