Ancient and Modern Genomes Reveal Microsatellites Maintain a Dynamic Equilibrium Through Deep Time.

Area of Science:

• Genetics
• Evolutionary Biology
• Bioinformatics

Background:

• Microsatellites are vital in population genetics but their evolutionary dynamics, particularly length stability over time, are poorly understood.
• Understanding microsatellite mutation processes is critical for accurate evolutionary modeling.

Purpose of the Study:

• To investigate the evolutionary dynamics of microsatellite loci over long timescales.
• To determine if microsatellite allele lengths drift over evolutionary periods.

Main Methods:

• Identification of over 27 million microsatellites from modern and ancient Adélie penguin genomes and 63 published chordate genomes.
• Analysis of microsatellite evolutionary dynamics across two timescales: Adélie penguin samples (~46.5 ka) and chordate diversification (>500 Ma).

Main Results:

• Microsatellite allele length evolution operates under dynamic equilibrium, with stable length distributions for specific loci despite individual polymorphism.
• Many microsatellites demonstrate persistence over extremely long evolutionary periods, especially within exons and regulatory sequences.
• Persistent microsatellites often maintain length variability, suggesting a role in preserving phenotypic variation.

Conclusions:

• Microsatellite lengths are evolutionarily stable, supporting their use in population genetics and evolutionary studies.
• The stability of microsatellite lengths has significant implications for interpreting genetic variation and evolutionary history.
• Microsatellites in functional genomic regions may contribute to phenotypic diversity within populations.