Mimicry overestimates and constraints

Mimicry is often the first conclusion jumped to when two coexisting plants resemble each other, or an organism. In many cases alternative explanations have not been investigated, and mimicry should not be established until they have been considered and appropriately excluded (Ruxton and Schaefer, 2011). Alternate hypotheses concerned with mimicry often exhibit fewer restrictions, and would therefore be more likely to allow the plant to evolve. Ruxton and Schaefer (2011) argue that the lack of elimination regarding alternate hypotheses is a massive restriction in current plant mimicry research. If researchers were to more clearly focus on deciphering a mechanism or applying the Ockham’s razor principle mimicry might not always be the hypothesised explanation (Ruxton and Schaefer, 2011). Researchers of plant adaptations need to consider convergent evolution and exploitations of sensory biases as alternative hypotheses to mimicry when attempting to explain similar aspects between plant species (Ruxton and Schaefer, 2011).

Mimicry in plants is also subject to many evolutionary constraints, and it can be concluded that there will always be a limit to a plants mimicking ability. One such constraint is the fact that plants are sessile, which presents multiple limitations (Williamson, 1982). The sessile nature of plants allows pollinators or herbivores time to assess the mimic and the model, and possibly decipher differences and learn how to distinguish between them. Another problem is that the pollinators or herbivores may recall the location that the mimic is in as being undesirable, the organism may have a bad experience and be deceived by the plant and learn not to visit that location again; being sessile the plant cannot change location. Another constraint on plant mimicry is their aggregation habits (Williamson, 1982). Species tend to clump together, a habit which can increase a visitor’s likelihood of visiting too many mimic plants and avoiding the area all together. Aggregation can also occur on the individual plant, with appendages such as fruit, flowers and leaves as the mimic signal transmitters; this aggregation having the same negative effect on a visitor as multiple plants (Williamson, 1982). Some deceptive species, such as the orchids, have evolved to limit aggregation by only occurring in small numbers and over wide spatial distances, so visitors are unable to have negative associations with individual plants. The sessile constraint can sometimes be avoided through the use of floral or seed mimicry, in which the appendages involved are only present for a short period of the plants lifespan. Aggregation constraints are perhaps the largest constraint on plant mimicry because visitor deception is much more successful and efficient if there are not many mimicking plants around, so they can never occur in large numbers (Williamson, 1982).