Evolutionary stability of one-to-many mutualisms

► I model a mutualism between one host individual and multiple symbiont individuals. ► Host preferentially chooses more cooperative symbionts from the environments. ► I concentrate the evolution of cooperativeness of symbiont to their host. ► Mutualists and cheaters can coexist stably in a symbiont population. ► Stronger preference of host may result in increase of cheater symbionts.