Fig. 4.

Dynamics of a resistance (or recall) allele. A DEG allele (homozygote females are sterile; homing rate =0.9) is introduced at a frequency of 1% in generation 1 and quickly spreads, imposing a population load. In a the DEG goes to fixation; we assume resistance alleles arise from EJ (one per thousand cleavage events) and such an allele quickly spreads, reducing the population load, initially rapidly and then more slowly. The dynamics are identical if instead of a resistance allele an artificially created recall allele is introduced. In b we assume that a resistance allele with the same parameters exists as a rare variant in the population at the time of DEG introduction (initial frequency 10⁻⁶). The allele spreads rapidly and the population experiences only a transient genetic load