Fig. 1.

Potential role of FIV in the maintenance of cat coat colour polymorphism. The results have been derived from the model presented in Supplementary material, with the following parameters: transmission rate of FIV between non-orange cats of 0.1; life expectancy of non-orange cats is 4 years; a selective advantage of orange cats in a disease-free population of 2.3%; reduction in life expectancy in FIV infected individuals of 10%; and relative transmission rate of FIV in orange cats of 5.75. One FIV-infected cat is released in the fully susceptible cat population at time t = 0. (a) Evolution of the proportion of orange cats in the population and (b) prevalence of FIV in orange (dashed line) and non-orange (solid line) cats. See Supplementary material for a full description of the model.