Catalogue number: Drawer 19
Wallace's specimen display to show how edible butterflies resemble (mimic) inedible butterfly species in order to avoid being eaten by predators.
In this drawer Wallace has arranged the 'uneatable' in the far right column and the 'eatable' to the left of them. Note that the males of two of the mimic species are not mimetic (don't resemble another species). This drawer illustrates the theory of Batesian mimicry, named after Wallace's friend and fellow naturalist Henry Walter Bates.
Bates and Wallace travelled together on an expedition to the Amazon region of South America. While collecting butterflies in Brazil, Bates caught many brightly coloured species that looked extremely similar to each other but were not closely related. Bates knew that some of these insects were distasteful to predators while others, which closely resembled them, were not. He therefore reasoned that the edible butterflies (the mimics) had evolved to resemble the inedible species (the models) in order to avoid being eaten by predators such as birds.
Milkweed butterflies (the models in this drawer) manufacture toxins or acquire them from plants when they are caterpillars or adults. These toxins result in the butterfly tasting horrible to predators, which means that predators avoid eating them. The mimic butterflies in this drawer belong to several unrelated butterfly groups, which have evolved to look like the toxic species which they fly together with. This gives them protection. Scientists are still trying to work out exactly why the males are not mimics - it is possibly linked to females being attracted to males by their colouring.
Wallace also made major contributions to the study of protective coloration in plants and animals, and proposed new concepts such as recognition markings and warning colours. Wallace first proposed 'warning colouration' in a letter he wrote to Charles Darwin, who was puzzled by the vivid colours of certain caterpillars, which could not be explained by his theory of sexual selection. Wallace thought the colours had probably evolved to warn predators that the caterpillars are distasteful.
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View high resolution scans and transcripts of Alfred Russel Wallace's correspondence, including all surviving letters between him and Charles Darwin.