Mitochondrion: Use in population genetic studies

The near-absence of genetic recombination in mitochondrial DNA makes it a useful source of information for scientists involved in population genetics and evolutionary biology. Because all the mitochondrial DNA is inherited as a single unit, or haplotype, the relationships between mitochondrial DNA from different individuals can be represented as a gene tree. Patterns in these gene trees can be used to infer the evolutionary history of populations. The classic example of this is in human evolutionary genetics, where the molecular clock can be used to provide a recent date for mitochondrial Eve. This is often interpreted as strong support for a recent modern human expansion out of Africa. Another human example is the sequencing of mitochondrial DNA from Neanderthal bones. The relatively large evolutionary distance between the mitochondrial DNA sequences of Neanderthals and living humans has been interpreted as evidence for lack of interbreeding between Neanderthals and anatomically modern humans.

However, mitochondrial DNA only reflects the history of females in a population, and so may not give a representative picture of the history of the population as a whole. For example, if dispersal is primarily undertaken by males, this will not be picked up by mitochondrial studies. This can be partially overcome by the use of patrilineal genetic sequences, if they are available (in mammals the non-recombining region of the Y-chromosome provides such a source). More broadly, only studies that also include nuclear DNA can provide a comprehensive evolutionary history of a population; unfortunately, genetic recombination means that these studies can be difficult to analyse.


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