evolutionary rate

Peterson GI & Masel J 2009 Quantitative prediction of molecular clock and K_a / K_s at short timescales. Mol Biol Evol 26:2595-2603.

• the apparent acceleration of the molecular clock at short timescales can be explained by segregating polymorphisms present at the time of the ancestral population, both neutral and slightly deleterious, and not newly arising slightly deleterious mutations