KIR polymorphism evolves only in populations having specific KIRs.

<p>The degree of KIR diversity (expressed as the Simspon's Reciprocal Index) increased only in populations having specific KIRs (i.e., for ), whereas in populations with degenerate KIRs it remained close to its initial value, reflecting largely neutral drift. The time plot in (A) represents the KIR diversity in a population infected with an MHC-downregulating virus, and the time plot in (B) shows the KIR diversity in populations infected with viruses evolving decoy molecules. Each line represents the mean of the SRI score, i.e. averaged over 10 different simulations. The different colors represent the specificity values ranging from to bits. (C) Mean SRI score at the end of the simulation for each specificity value. There is a significant difference in the SRI score between the infection with an MHC down-regulating virus (red) and an infection with a virus evolving decoy molecules (black) (* represent <i>p</i> values and ** <i>p</i> values, Mann-Whitney <i>U</i> test. The boxes represent the interquartile range, the thick horizontal lines represent the median, and the circles are outliers.).