Evolvability tradeoffs in emergent digital replicators

TL;DR

This study uses digital evolution to investigate how emergent self-replicators differ in their capacity to evolve, revealing a trade-off between optimizing replication and acquiring innovations, linked to their replication machinery structure.

Contribution

It introduces a classification of emergent digital replicators based on their evolvability traits and explores the structural basis of these differences.

Findings

Two classes of emergent replicators with distinct evolvability profiles.

A trade-off exists between optimizing replication and acquiring innovations.

Replication machinery structure influences evolvability traits.

Abstract

The role of historical contingency in the origin of life is one of the great unknowns in modern science. Only one example of life exists--one that proceeded from a single self-replicating organism (or a set of replicating hyper-cycles) to the vast complexity we see today in Earth's biosphere. We know that emergent life has the potential to evolve great increases in complexity, but it is unknown if evolvability is automatic given any self-replicating organism. At the same time, it is difficult to test such questions in biochemical systems. Laboratory studies with RNA replicators have had some success with exploring the capacities of simple self-replicators, but these experiments are still limited in both capabilities and scope. Here, we use the digital evolution system Avida to explore the interaction between emergent replicators (rare randomly-assembled self-replicators) and evolvability. We find that we can classify fixed-length emergent replicators in Avida into two classes based on functional analysis. One class is more evolvable in the sense of optimizing their replication abilities. However, the other class is more evolvable in the sense of acquiring evolutionary innovations. We tie this trade-off in evolvability to the structure of the respective classes' replication machinery, and speculate on the relevance of these results to biochemical replicators.