Figure 1.

Allele frequencies, wild genotype frequency and population fitness over time after the release of killer–rescue strains with no fitness costs to the K or R alleles. (a) Single release of the homozygous killer–rescue strain at a 2 : 1 ratio relative to the wild population, resulting in a K and R initial frequency of 0.66, one killer gene. (b) As in (a) except that there is a 1 : 2 release, initial frequency of 0.33. (c) Releases at 1 : 2 ratio in each of the first four generations, one killer gene. (d) A single release at a 1 : 2 ratio of a strain that is homozygous for two insertions of K and one insertion of R. In all cases, the sex ratio of released individuals is 1 : 1. Dash-dotted line, wild-type (kkrr); dotted line, K allele; dashed line, R allele; solid line, mean fitness.