Onset of natural selection in auto-catalytic heteropolymers

Abstract

(AVT) and maslov@illinois.edu (SM)Reduction of information entropy along with ever-increasing complexity are among the key signatures of living matter. Understanding the onset of such behavior in early prebiotic world is essential for solving the problem of origins of life. To elucidate this transition, we study a theoretical model of informationstoring heteropolymers capable of template-assisted ligation and subjected to cyclic non-equilibrium driving forces. We discover that this simple physical system undergoes a spontaneous reduction of the information entropy due to the competition of chains for constituent monomers. This natural-selectionlike process ultimately results in the survival of a limited subset of polymer sequences. Importantly, the number of surviving sequences remains exponentially large, thus opening up the possibility of further increase in complexity due to Darwinian evolution. We also propose potential experimental implementations of our model using either biopolymers or artificial nano-structures.

Multistability and regime shifts in microbial communities explained by competition for essential nutrients

“…Yet, the model in Ref. 50 is capable of (at least) bistability. At present, it is not clear if this is due to autocatalytic cycles having length 2 or this property would survive in a simpler version of the model in which instead of the Eq.…”

“…and the overall fluxes of left and right ends are independent from each other (instead of both being equal to c i = φ i /δ as in Ref. 50 ).…”

“…However, many of the essential results we obtained (e. g. possible multistability in a system where species have different yields) hold for any growth laws listed above. In fact, the low concentration version of the previous growth law, where g (m) α c i •n j has been studied by one of us in the context of autocatalytic growth of heteropolymers 50 . Instead of exponentially replicating microbial species Ref.…”

“…Instead of exponentially replicating microbial species Ref. 50 considers pairs of mutually catalytic (and thus exponentially growing) complementary "2-mers" (a specific sequence of two consecutive monomers anywhere within a polymer chain). This minor difference complicates the math, while leaving the basic properties unchanged.…”

How did prebiotic polymers become informational foldamers?

“…They envision that some of the RNA chains can spontaneously serve as polymerase ribozymes, leading to autocatalytic elongation of other RNAs. A related model asserts that autocatalytic chain elongation arises from template-assisted ligation and random breakage [13]. These are models of the 'pre-informational' world before heteropolymers begin to encode biological sequence-structure relationships.…”