{<i>Ud</i>}86 population experiments demonstrating strong underdominance.

<p>(<b>A</b>) Multigenerational population experiments showing the frequency change in transgenic individuals from various starting frequencies (blue lines). Populations with starting values higher than the estimated threshold allele frequency of 0.61 (straight bold dashed line) proceed to fixation while those below result in loss of {<i>Ud</i>}86 (verified by crosses and PCR in all 12 populations). Dashed lines indicate predicted trajectories, under the maximum likelihood estimate (MLE) of fitness parameters shown in parts b and c. (<b>B</b>) Likelihood surface of relative fitness estimates. Fitness is inferred from the change in allele frequencies in A (<b>C</b>) MLE fitness estimates of the transgenic genotypes.