Figure 2
Comparison of the rate of selection between diploids and autotetraploids. The figure plots the number of generations for mean fitness of a population to reach 90% of maximum possible fitness as a function of recombination rate for a diploid population (squares), an autotetraploid population that assumes the diploid gamete pool model without double reduction (black circles) and with double reduction (gray circles), and an autotetraploid population that assumes the haploid gamete pool model without double reduction (black triangles) and with double reduction (gray triangles). In the diploid gamete pool model chromosomal gametic disequilibrium may occur, and in the haploid gamete pool model chromosomal gametic disequilibrium does not occur (see Materials and Methods). For a given recombination rate circular and triangular points are staggered to avoid overlap. There are no points plotted for the diploid population beyond a recombination rate of 1/20 because the population did not reach 90% of the maximum possible fitness within 50 000 generations. For the autotetraploid population it is assumed that the recombination rate between the centromere and locus A (q) and between locus A and locus B (r) are the same. Fitness follows the concave-down parameter set for the adaptive epistatic combination (part [a] of Figure 1) and the additive deleterious model (part [a] of Supplementary Figure 1). Selection parameters are ξ1=ξ2 =− 0.01 and γ=0.1. The mutation rate at the allelic level is μ=10−5. Without double reduction the remaining parameters are τ=2/3, pPC=0 and pDP=0. With double reduction the remaining parameters are τ=2/3, pPC=1/3 and pDP=1/3.
