Simple Sequence Length Polymorphisms (SSLPs) are used as genetic marker

Genetic marker

A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify cells, individuals or species. It can be described as a variation that can be observed...

s with Polymerase Chain Reaction (PCR)

Polymerase chain reaction

The polymerase chain reaction is a scientific technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence....

. An SSLP is a type of polymorphism

Polymorphism (biology)

Polymorphism in biology occurs when two or more clearly different phenotypes exist in the same population of a species — in other words, the occurrence of more than one form or morph...

: a difference in DNA

DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...

 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 variance between two individuals in a certain species.

Applications

An example of the usage of SSLPs (microsatellites) is seen in a study by Rosenberg et al., in which Rosenberg and his team used SSLPs to cluster different continental races. The study was critical to Nicholas Wade

Nicholas Wade

Nicholas Wade is a British-born scientific reporter, editor and author who currently writes for the Science Times section of The New York Times.-Biography:Wade was born in Aylesbury, England and educated at Eton College and King's College, Cambridge...

's New York Times Bestseller, Before the Dawn: Recovering the Lost History of Our Ancestors.

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

Phenotype

A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...

s of the individuals, thus being unaffected by natural selection

Natural selection

Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....

.