Fig. 2.
Selection can occur in prelife without replication. The equilibrium abundances of all sequences of length 1 to 6 are shown as a function of the intensity of selection, s. There are 2n sequences of length n. (A) In a random prelife landscape, half of all reactions occur at rate 1 + s, the other half at rate 1. As s increases, a small subset of sequences is selected, whereas the others decline to very low abundance. (B) All reactions leading to the one “master sequence” of length 6 occur at rate b = 1 + s, all others at rate a = 1. As s increases, the master sequence is selected. Lineages that share sequences with the master sequence are suppressed, whereas other lineages are unaffected. Color code: black, gray, green, light blue, blue, and red for sequences of length 1 to 6, respectively. Other parameters: a0 = a1 = 1/2 and d = 1.