Dynamics of repeat polymorphisms under a forward-backward mutation model: within- and between-population variability...

Area of Science:

• Population Genetics
• Molecular Evolution
• Bioinformatics

Background:

• Microsatellite loci evolve through forward-backward mutations, influencing allele size.
• Understanding microsatellite variation is key to estimating population divergence.
• Existing genetic distance measures may be affected by mutation complexities.

Purpose of the Study:

• To develop a robust mathematical measure of genetic distance based on microsatellite variation.
• To assess the proportionality of this measure to population divergence time under various mutation models.
• To apply the new measure to human population data and evaluate its consistency with ethnohistory.

Main Methods:

• Developing a mathematical framework for genetic distance using variance components of microsatellite allele sizes.
• Modeling the impact of forward-backward mutations on allele size changes.
• Applying the derived genetic distance measure to empirical data from 18 microsatellite loci in nine human populations.

Main Results:

• A novel genetic distance measure was formulated based on microsatellite allele size variation.
• The measure demonstrates proportionality to population divergence time, robust to variable and biased mutation rates.
• When population size and mutation rate are constant, the measure is directly proportional to divergence time.
• Application to human population data yielded evolutionary trees congruent with established ethnohistorical records.

Conclusions:

• The proposed genetic distance measure offers a reliable tool for estimating population divergence times from microsatellite data.
• This method is resilient to complexities in microsatellite evolution, such as biased mutation.
• The findings support the utility of microsatellite variation for reconstructing human population history.