Figure 1. Extinction decreases with number of invading alleles.
(a) The dynamics of invasions. Observed number of GFP individuals, when two or five individuals initially invade a population with N=103 wild-type individuals. Thirty-five replicates were used in the experiments starting with two GFP individuals, whereas 56 replicates were followed in the invasions with five GFP individuals. (b) Observed probability of extinction at G5 with 2 s.d. of 1,000 bootstrap replicates is shown as the error bars. (c,d) Selection coefficient estimates. For the two-individual (c) and five-individual (d) GFP invasion experiments, the likelihood values of selective coefficients (s) for the observed GFP allele counts at G3, G4 and G5 are presented. These were obtained by simulations of 108 invasions. In the region close to the initial ML estimate, defined as ML-10log10 (black circles), an extra set of 9 × 108 simulations were performed. A quadratic function was then fitted to this interval (dashed line) to obtain the final ML estimate of s (grey line) with −2log10 confidence limits (grey area).