Evolution and persistence of obligate mutualists and exploiters: competition for partners and evolutionary immunization

摘要: Mutualisms are ubiquitous in nature, as is their exploitation by both conspecific and heterospecific cheaters. Yet, evolutionary theory predicts that cheating should be favoured natural selection. Here, we show theoretically asymmetrical competition for partners generally determines the fate of obligate mutualisms facing third-species invaders. When asymmetry partner relatively weak, mutualists may either exclude exploiters or coexist with them, which case co-evolutionary response to usually benign. strong, evolve towards attractors where they become extremely vulnerable exploiter invasion. However, invasion at an early stage mutualism's history can deflect mutualists' trajectories slightly different confer long-term stability against further exploitation. Thus, coexistence often involve historical effect whereby co-opted mutualism provide lasting 'evolutionary immunization'