Fig. 1.

Prebiological coevolution of reproducers and replicators: a conceptual scenario and model framework. Protocells with (blue) and without (yellow) GE compete for common resources (black circles). The double outline denotes the lipid bilayer membrane of the protocells. The GE in the protocells are either autonomous (purple) or nonautonomous (green). Autonomous elements replicate themselves if the resources are present. Nonautonomous GE replicate by interacting with autonomous elements. Both types of protocells can reproduce once their resources exceed some threshold value (in the depicted case, the arbitrarily set threshold is seven units of resources for both protocell types). Successful reproduction yields two daughter cells. The probability of successful reproduction of the GE-containing (blue) cells depends on the composition of GE in the reproducing protocell $p\left(m_{\mathcal{A}},m_{\mathcal{N}}\right)$ , where $m_{\mathcal{A}}$ and $m_{\mathcal{N}}$ are the numbers of autonomous and nonautonomous GE, respectively. The probability of successful reproduction is constant for the GE-less (yellow) cells. If reproduction is successful, then, the daughter cells inherit the resources of the mother protocell, as well as GE, in the case of blue protocells. A reproducing cell dies in case of unsuccessful reproduction (Upper Left and Bottom Right), resulting in the dissipation of all resources and extinction of all GE. Protocells can also die due to the lack of resources (upper right blue protocell and bottom left yellow protocell).