Fig. 3.

Timing of the TCC $\to$ TTC pulse in Europeans. (A) The relative composition of TCC $\to$ TTC variants (centered log ratio transform) (Materials and Methods) in each frequency class for each European population (open circles) shows an excess at intermediate frequencies. The expected values fit using the inferred MuSH are shown as points connected by lines. (B) The inferred TCC $\to$ TTC mutation rate histories (in units of mutations per ascertained genome per generation); MuSH inference was performed using a mixture of order 0 and order 3 trends (Materials and Methods and SI Appendix, Figs. S6–S8) for both demography and MuSH. CEU, Utah residents with Northern and Western European ancestry; GBR, British in England and Scotland; IBS, Iberian population in Spain; TSI, Toscani in Italia.