Figure 2. Vulnerable hosts in Avida have fewer and more generalist parasites.

Host extinction risk was measured as h/H, with h being the ordinal position in the extinction sequence of the target host as assessed after the coevolution phase, and H being host richness. Parasite richness (a) and host range (b) were measured, respectively, as the average fraction of parasites infecting a host, and of hosts used by a parasite. Solid lines and dots indicate average values. The Spearman-rank correlation coefficient was computed on all raw data (that is, not on the averaged values shown in the plots). Boxes indicate first and third quartiles, whiskers indicate range values and horizontal lines indicate median values.