Figure 4 in Reproductive isolation and the causes of speciation rate variation in nature

Figure 4. Some possible relationships between the rate at which lineages evolve reproductive isolation and their rate of speciation. A, direct correspondence, where the evolution of reproductive evolution shows a one-to-one relationship with the macroevolutionary rate of speciation. In this scenario, the evolution of reproductive isolation is the exclusive determinant of macroevolutionary speciation dynamics. B, offset/dampened relationship, where the rate of evolution of reproductive isolation is the dominant control on speciation rates, although speciation rates are lower than predicted by the rate of evolution of reproductive isolation alone. This relationship implies that many populations evolving reproductive isolation fail to persist through deep time. C, decoupled, such that reproductive isolation shows no predictive relationship with macroevolutionary speciation rates. This scenario suggests that reproductive isolation is not the rate-limiting control on the rate of speciation. Adapted from Rabosky (2013).