We use the three strain model described before to study the impact of the mutation rate, m, and the average reproductive number of the intermediate strain, a 2 , on the probability of emergence per introduction in a single, infinite population. We assume 0vmƒ10 {1 as an illustrative spectrum of possible mutation rates. Figure 2 shows the probability of emergence for different mutation rates and average reproductive numbers of the intermediate strain. Not surprisingly, the probability of emergence grows non-linearly with a 2 and m. The probability of having no mutation in the second strain is (1zm) {x where x is the number of infected hosts with strain 2. While the intermediate reproductive number affects the exponent, the mutation rate has a direct influence on the base. We validate our analytical results by comparing them with the average probability of emergence of 10 3 simulated emergence processes, using one homogeneous population as described in (1). Figure 2 reveals an excellent agreement between the analytical results and simulations.