Sometimes, a band is obtained with both parents using the marker-specific primers. The technical reasons for this are complex, but we have found that it is possible to obtain sequence information from the fragment amplified from both parents and to identify sequence differences between them. Sequence differences between the two versions of the locus can sometimes lead to differences in sites recognised by DNA restriction enzymes. This means that the fragment of DNA produced from one parent can be cut into smaller fragments by a selected restriction enzyme but the fragment from the other parent cannot or at least is cut into different sized fragments. Although the use of such CAPS markers is slightly more time-consuming, it offers the advantage to geneticists that it is possible to detect individuals that contain both versions of the locus.
Molecular markers can also be extremely useful to aid the identification of biological material.
We are all familiar with the concept of human DNA fingerprinting as used in forensic science. This makes use of differences in DNA sequences between individual people to allow their identification using very small samples of tissue from their bodies. However, in many situations identification of species rather than individuals is extremely important to biologists. Sometimes species recognition can be very difficult because there may be many very similar species that are difficult to identify. In other cases a single specimen may be incomplete or does not show the important identifying characters at that particular time.