Simple Sequence Length Polymorphisms (SSLPs) are used as
genetic marker A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. It can be described as a variation (which may arise due to mutation or alteration in the genomic loci) that can be ...
s with
polymerase chain reaction (PCR)
The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) ...
. An SSLP is a type of
polymorphism: a difference in
DNA sequence amongst individuals. SSLPs are repeated sequences over varying base lengths in intergenic regions of deoxyribonucleic acid (DNA). Variance in the length of SSLPs can be used to understand
genetic variation between two individuals in a certain species.
Applications
An example of the usage of SSLPs (
microsatellites
A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...
) is seen in a study by Rosenberg et al., where SSLPs were used to cluster different continental populations of human beings.
The study was critical to
Nicholas Wade's New York Times Bestseller, ''
Before the Dawn: Recovering the Lost History of Our Ancestors''.
[Wade, Nicholas (2006). ''Before the Dawn: Recovering the Lost History of Our Ancestors''. Penguin Press. ]
Rosenberg Study
Rosenberg studied 377 SSLPs in 1000 people in 52 different regions of the world. By using
PCR and
cluster analysis, Rosenberg was able to group individuals that had the same SSLPs . These SSLPs were extremely useful to the experiment because they do not affect the
phenotype
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological pr ...
s of the individuals, thus being unaffected by
natural selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Cha ...
.
[{{cite journal , last=Rosenberg , first=N. A. , title=Genetic Structure of Human Populations , journal=Science , publisher=American Association for the Advancement of Science (AAAS) , volume=298 , issue=5602 , date=2002-12-20 , issn=0036-8075 , doi=10.1126/science.1078311 , pages=2381–2385 , pmid=12493913, bibcode=2002Sci...298.2381R , s2cid=8127224 ]
References
Polymorphism (biology)