Abstract:

Advances in research on the evolution of cooperation has provided new insights into our understanding of plant-pollinator interactions. Plants can build a cooperative interaction with pollinators by providing a reward for the pollinators’ services. As we see it, three key questions surround the establishment, maintenance, and breakdown of plant-pollinator cooperation: (1) How can plants and pollinators recruit optimal partners within the context of deficient information about each other prior to actually establishing the interaction? (2) How can the mutualists limit the spread of cheating strategies (e.g. nectar robbing and deceit pollination) to maintain cooperative interactions? (3) What processes can lead to the breakdown of the cooperation between plants and pollinators? The signaling and screening interactions that occur between plants and pollinators could work to promote cooperation. Pollinators and plants use partner choice and defensive strategies, respectively, to cope with cheating strategies. In some situations, the stable coexistence of cooperators and cheaters could be helpful to maintain the plant-pollinator cooperation. There are three processes, shifts from mutualism to antagonism, switches to novel partners and mutualism abandonment, which will cause the breakdown of plant-pollinator cooperation. We highlight experimental results that support some of the theoretical predictions discussed above. These results help to identify key mechanisms related to plant-pollinator cooperation. Four subjects for future research on plant-pollinator cooperation are highlighted in this paper: (1) selection on the honest signaling of plants by pollinators, and the effectiveness of screening mechanisms provided by plants; (2) potential mechanisms adopted by plants and pollinators for dealing with cheaters, and relative importance of these mechanisms; (3) mechanisms which allow the stable coexistence of cooperators and cheaters; (4) response of plant-pollinator cooperative systems to global change.

Key words: cooperation, game theory, benefit-cost, defective strategies, species coexistence