Evolution of Multicellular Specialization in Dynamic Fluids

Multicellularity and division of labor mark a major transition in the development of life. In this study, we determine the conditions for multicellular specialization to occur starting with a system of generalists that secrete two public goods. We look at two different fitness functions where either both public goods are necessary for any fitness gain or where either one is sufficient for a fitness gain. We denote these by AND and OR respectively, to resemble the logical AND and OR functions. Social structures arise naturally from our advection-diffusion-reaction model as self-replicating Turing patterns. We see that an AND structure is necessary for the specialists to stay together in the same social structure. Specialists in the OR case dissociate into separate groups of pure specialists. We look at the effects of varying the cost of cooperation and mutation rate on the emergence of specialization. When trade-off costs are small, we see that spatial structure can help facilitate the transition to specialization for either fitness function. At larger trade-offs in the AND case, we see that generalists are more stable.