Title: Templated ligation can create a hypercycle replication network,
Abstract: The stability of sequence replication was crucial for the emergence of
molecular evolution and early life. Exponential replication with a first-order
growth dynamics show inherent instabilities such as the error catastrophe and
the dominance by the fastest replicators. This favors less structured and short
sequences. The theoretical concept of hypercycles has been proposed to solve
these problems. Their higher-order growth kinetics leads to frequency-dependent
selection and stabilizes the replication of majority molecules. However, many
implementations of hypercycles are unstable or require special sequences with
catalytic activity. Here, we demonstrate the spontaneous emergence of
higher-order cooperative replication from a network of simple ligation chain
reactions (LCR). We performed long-term LCR experiments from a mixture of
sequences under molecule degrading conditions with a ligase protein. At the
chosen temperature cycling, a network of positive feedback loops arose from
both the cooperative ligation of matching sequences and the emerging increase
in sequence length. It generated higher-order replication with
frequency-dependent selection. The experiments matched a complete simulation
using experimentally determined ligation rates and the hypercycle mechanism was
also confirmed by abstracted modeling. Since templated ligation is a most basic
reaction of oligonucleotides, the described mechanism could have been
implemented under microthermal convection on early Earth.