Evolution of the division of labour between templates and catalysts in spatial replicator models.

The central dogma of molecular biology can be conceptualised as the division of labour between templates and catalysts, where templates transmit genetic in- formation, catalysts accelerate chemical reactions, and the information flows from templates to catalysts but not from catalysts to templates. How can the template- catalyst division evolve in primordial replicating systems? A previous study has shown that even if the template-catalyst division does not provide an immediate fit- ness benefit, it can evolve through symmetry breaking between replicating molecules when the molecules are compartmentalised into protocells. However, cellular com- partmentalisation may have been absent in primordial replicating systems. Here, we investigate whether cellular compartmentalisation is necessary for the evolution of the template-catalyst division via symmetry breaking using an individual-based model of replicators in a two-dimensional space. Our results show that replicators evolve the template-catalyst division via symmetry breaking when their diffusion constant is sufficiently high, a condition that results in low genetic relatedness between replicators. The evolution of the template-catalyst division reduces the risk of invasion by "cheaters," replicators that have no catalytic activities, encode no catalysts, but replicate to the detriment of local population growth. Our results suggest that the evolution of the template-catalyst division via symmetry breaking does not require cellular compartmentalization and is, instead, a general phenomenon in replicators with structured populations.