Factors affecting germline mutations in a hypervariable microsatellite: a comparative analysis of six species of swallows (Aves: Hirundinidae).

Microsatellites mutate frequently by replication slippage. Empirical evidence shows that the probability of such slippage mutations may increase with the length of the repeat region as well as exposure to environmental mutagens, but the mutation rate can also differ between the male and female germline. It has been hypothesized that more intense sexual selection or sperm competition can also lead to elevated mutation rates, but the empirical evidence is inconclusive.