Seed dispersal by deception: A game between mimetic seeds and their bird dispersers

Mimetic seeds attract birds to disperse seeds mainly by mimicking fleshy fruits or arillate seeds, however, they provide little nutritive reward for bird dispersers. The key characteristics of mimetic seeds are conspicuous seed color, hard seed coat, certain toxic secondary metabolites, and perhaps smooth waxy layer. In this review, we discuss the global distribution of mimetic seeds, the interaction of mimetic seeds with bird dispersers, and secondary metabolites that underlie key characteristics of mimetic seeds. Mimetic-seed species mainly occur in the tropics, with large numbers distributed along coastal areas. The interaction between mimetic-seed species and bird dispersers can be antagonistic, mutualistic, or both. These interactions are generally established by conspicuous visual cues and hard tactile cues from mimetic seeds. The formation and variation of key characteristics of mimetic seeds may contribute to the metabolism of several kind of secondary compounds. Here, we also discuss mimetic-seed dispersal in the context of an evolutionary game, and propose several aspects of mimetic-seed dispersal that remain unstudied. While this review is based on preliminary findings and does not account for other potential influencing factors such as climate, it is expected to contribute to an improved understanding of mimetic-seed dispersal.