10. Microsatellites
Generally in our work in the Evolutionary Biology Unit we are looking at genetic differences between individuals ie polymorphisms. An important class of polymorphisms are the microsatellite repeats - one to six base pair repeats (e.g. (CA)n or (AAT)n) which are found throughout the genome of organisms ranging from yeasts through to mammals.
Microsatellites have high mutation rates and therefore may show high variation between individuals within a species for example. This makes them ideal for determining relationships between different populations of the same species (ie population genetics) or even between individuals. Microsatellites can be used to determine family relationships within groups and therefore to study social behaviour within natural populations. They have even been used in determining historic genetic diversity by looking at very old museum specimens. Aside from their use in population and conservation biology, microsatellites have also proven useful in the study of genetic disease and forensics, for example.
This is what the sequence of a microsatellite repeat might look like. It is a fragment of DNA showing two different individuals with a variable number of repeat units (CA is the repeat unit).
(CA) 13
individual 1
(CA) 15
individual 2
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