Data from: Ancient and modern genomes reveal microsatellites maintain a dynamic equilibrium through deep time

Microsatellites are widely used in population genetics, but their
evolutionary dynamics remain poorly understood. It is unclear whether
microsatellite loci drift in length over time. This is important because
the mutation processes that underlie these important genetic markers are
central to the evolutionary models that employ microsatellites. We
identify more than 27 million microsatellites using a novel and unique
dataset of modern and ancient Adélie penguin genomes along with data from
63 published chordate genomes. We investigate microsatellite evolutionary
dynamics over two time scales: one based on Adélie penguin samples dating
to approximately 46.5 kya, the other dating to the diversification of
chordates more than 500 Mya. We show that the process of microsatellite
allele length evolution is at dynamic equilibrium; while there is length
polymorphism among individuals, the length distribution for a given locus
remains stable. Many microsatellites persist over very long time scales,
particularly in exons and regulatory sequences. These often retain length
variability, suggesting that they may play a role in maintaining
phenotypic variation within populations.