The highlighted sections are examples of microsatellites.
A microsatellite is a short DNA sequence made up of nucleotides that are repeated in tandem. The units that are repeated are either mono-, di-, tri-, tetra-, or pentanucleotides.1 In diploid organisms, an individual will always have two copies of each of it’s microsatellites. The number of repeats of a sequence will vary by individual.2 Over time certain microsatellites will continue to circulate through a population, therefore making certain groups of microsatellites typical of certain populations. Occasionally DNA polymerase adds another repeat to the sequence. In the event of a mutation, the new microsatellite can be passed on to offspring who will usually create accurate replications of the sequence.3
Microsatellites have been useful in many ways as genetic markers. This is largely because they are widely spread within the genome, polymorphic, and transferable between species.3 They are especially useful for genome mapping, genetic diversity analysis, individual identification, population and phylogenetic relationships, bio-invasions, and epidemiology.3
References:
1. McDonald, D. (2008, January 1). Molecular Marker Glossary. Retrieved March 17, 2015.
2. Allender, C. (2004, January 1). Microsatellite Information Exchange. Retrieved March 17, 2015
3. Andrea Akemi Hoshino, Juliana Pereira Bravo, Paula Macedo Nobile and Karina Alessandra Morelli (2012). Microsatellites as Tools for Genetic Diversity Analysis, Genetic Diversity in Microorganisms, Prof. Mahmut Caliskan (Ed.), ISBN: 978-953-51-0064-5, InTech