FIGURE 2.
The functional nature of selection. (A) Selection for constant danger pool product concentrations. Mean pool age is 20 d, with 5 mM mean nucleotide supplies. Probabilities are shown before (blue dashed, Pprod) and after (ochre solid, Pselected) a cycle of strong selection (black dashed, Pselect, right y-axis). Normalized probabilities are calculated from 1000 pools (unselected) and 642 pools (after selection). The first bin is 10−10 M wide, all other bins are 1.5 × 10−4 M. Blue arrow at top left points to inactive pools (0.000 M product). (B) Product dispersion versus pool age. The same mean age and nucleotide concentration as in C and D are used. Triangles are pools in constant danger, circles pools in periodic danger. (C) Pool progress toward templating (Δftemp) at differing product dispersions (SD/mean). Using 20 d, 5 mM pools as A, Δftemp is plotted versus initial, unselected pool product dispersion (SD/mean). Triangles are strongly selected constant danger pools (sporadically and simultaneously fed). Circles are mildly selected constant danger pools (sporadically and simultaneously fed). Points are ordered (Fig. 2B), early pools on the right, late to the left (see text). (D) Pool progress toward templating (Δftemp) at differing stringencies (1/sfsel). Using 20 d, 5 mM pools as A, Δftemp is plotted versus selection stringency (1/sfsel). Triangles are strongly selected constant danger pools (sporadically and simultaneously fed). Circles are mildly selected constant danger pools (sporadically and simultaneously fed).