Dynamical interactions among compositionally distinct protocell populations and its implications for evolution of early membranes

The spontaneous self-assembly of single chain amphiphiles (SCAs) would have resulted in multiple protocell species in an early-Earth niche. Considering the heterogeneity inherent in a prebiotic milieu, interactions between physicochemically distinct protocell populations was evaluated to discern if emergent properties occurred at a systems level. This study demonstrates that depending on the physicochemical properties of the membrane, interacting populations are endowed with varied emergent properties owing to their coexistence. In a multispecies paradigm involving a two-candidate protocell system, the fitter population acted as a predator and grew at the expense of the less-fit prey population. The observed growth could be attributed to the predator attaining a more robust membrane via chemical evolution. Importantly, the prey population also accrued emergent properties like molecular crowding, and coexist in balance with the predator population, without being completely outcompeted. When extrapolating these results to a three-candidate population, the outcomes were multipronged. These findings suggest a possible route for protocell membrane evolution that could have occurred even in the absence of any sophisticated protein machinery, benefitting coexisting populations, while also illustrating evolutionary trajectories that potentially resulted in functionally complex protocells.