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Keywords:

  • carnivorous plants;
  • evolutionary convergence;
  • exploitation of perceptual bias;
  • pitcher plants;
  • plant population and community dynamics

Summary

1. Based upon similarity in visual or olfactory appearances, recent studies concluded that mimicry of plants or plant parts occurs in distinct systems, in carnivorous plants that mimic flowers to increase capture success, in thorny plants to defend themselves against predators and in parasitized ants to increase parasite dispersal.

2. Taking the example of the carnivorous plant Nepenthes rafflesiana emitting volatiles that insects find attractive, and that also occur in flowers, we argue here that two alternative explanations are more plausible than mimicry: exploitation of perceptual bias and convergence.

3. Exploitation of perceptual bias requires only the well-established phenomenon of generalization of rewarding (or unrewarding) experiences; and does not require mimicry’s more specialized conditions of sufficient similarity of the mimic to a specific model, as well as consistency in the overlaps of their phenology and distribution, to cause misidentification by animals.

4. Like most flowers, the pitchers of N. rafflesiana offer a nectar reward to visiting insects. Evolution acting on both flowers and pitchers may have converged on the use of similar volatiles entirely independently, simply because these volatiles are effective at attracting nectar-seekers.

5. We conclude that not only are there currently no demonstrations of mimicry of a flower’s scent among carnivorous plants, there is also no evidence that mimicry (in any sensory modality) plays any part in carnivory by plants.

6.Synthesis. Researchers should guard against prematurely accepting intuitively appealing explanations of mimicry that may hinder the search for the true mechanisms underlying the evolution of some fascinating insect–plant interactions.