Molecular marker

Molecular markers are DNA sequences that can be identified by a simple assay, allowing the presence or absence of neighbouring stretches of the genome to be inferred. The marker may be short, such as a single base-pair change (Single Nucleotide Polymorphism) or long, such as a DNA fragment generated by a restriction digest. The marker may be identified directly, for example by DNA sequencing, or indirectly, as in the case of allozymes