Saturation

Genetic saturation is the reduced appearance, which occurs over time, of sequence divergence rate that results from reverse mutations, homoplasmies and other multiple changes occurring at single sites along two genetic lineages.

Genetic saturation is a cause of reticulation in genetic trees, where diverging genetic branches might fuse back into one another before splitting. Two other causes are sequence errors and recombination.

Genetic saturation occurs most rapidly on rapidly evolving sequences, such as the hypervariable region of mitochondrial DNA, or in short tandem repeats such as on the Y-chromosome.