pathogen infects leaves of blueberries, causing them to secrete sugars, in effect mimicking the nectar of flowers. To the naked eye the leaves do not look like flowers, yet they still attract pollinating insects like bees using an ultraviolet signal. This case is unusual, in that the fungus benefits from the deception but it is the leaves that act as mimics, being harmed in the process. It is similar to host-parasite mimicry, but the host does not receive the signal. It has something in common with automimicry, but the plant does not benefit from the mimicry, and the action of the pathogen is required to produce it. Evolution It is widely accepted that mimicry evolves as a positive adaptation. The lepidopterist and novelist Vladimir Nabokov however argued that although natural selection might stabilize a "mimic" form, it would not be necessary to create it. The most widely accepted model used to explain the evolution of mimicry in butterflies is the two-step hypothesis. The first step involves mutation in modifier genes that regulate a complex cluster of linked genes that cause large changes in morphology. The second step consists of selections on genes with smaller phenotypic effects, creating an increasingly close resemblance. This model is supported by empirical evidence that suggests that a few single point mutations cause large phenotypic effects, while numerous others produce smaller effects. Some regulatory elements collaborate to form a supergene for the development of butterfly color patterns. The model is supported by computational simulations of population genetics. The Batesian mimicry in Papilio polytes is controlled by the doublesex gene. Some mimicry is imperfect. Natural selection drives mimicry only far enough to deceive predators. For example, when predators avoid a mimic that imperfectly resembles a coral snake, the mimic is sufficiently protected. Convergent evolution is an alternative explanation for why organisms such as coral reef fish and benthic marine invertebrates such as sponges and nudibranchs have come to resemble each other. See also Biomimicry Chemical mimicry Locomotor mimicry Molecular mimicry Preadaptation Semiotics Mimic octopus Notes References Further reading (a supplement of volume 131 of the journal American Naturalist dedicated to E. B. Ford). Cott, H. B. (1940) Adaptive Coloration in Animals. Methuen and Co, London, Edmunds, M. 1974. Defence in Animals: a survey of anti-predator defences. Harlow, Essex and New York, Longman. . Owen, D. (1980) Camouflage and Mimicry. Oxford University Press, . Stevens, M. (2016). Cheats