Dynamical interactions among protocell populations: Implications for membrane-mediated chemical evolution

Abstract

The spontaneous self-assembly of single chain amphiphiles 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 an emergent property, that of molecular crowding, and continued to coexist 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. This also highlights the benefits of synergism in coexisting protocell populations, illustrating putative evolutionary trajectories that eventually could have resulted in functionally complex protocells.