The evolution and maintenance of floral rewardlessness

AbstractThis chapter examines the evolutionary factors behind the losses and gains of floral rewards. While mimicry is associated with plant lineages that lack floral rewards, rewardlessness and mimicry are not synonymous. Pollination typically takes the form of a biological transaction, whereby plants offer a material reward in exchange for a sexual service facilitated by animals. This is considered as a mutualism because both partners benefit but in reality these systems involve intense mutual exploitation—either partner will readily “cheat” if provided with the opportunity to do so. Not all deceptive plant species rely on mimicry (some rely solely on generalized attractive signals), but there is certainly a strong association between floral rewardlessness and various forms of mimicry. A key question is whether rewardlessness generally evolved before, together with, or after the evolution of mimicry in plant lineages, and this issue is explored in this chapter.