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The other, Henry Walter Bates, stayed longer: eleven years. After a long time enjoying good health, he got Malaria and decided to go back to England (Stearn, 1981). Bates developed a deep interest in the region, the fauna, the people and their costumes, which he described beautifully in gThe Naturalist on the river Amazonsh (1876). His studies on butterflies led him to propose the theory of mimicry, read at a meeting of the Linnean Society of London in 1861 and published in the following year under the titlegContributions to an insect fauna of the Amazon Valleyh in the Transactions of the Linnean Society.
The high diversity of bright, conspicuous color patterns of neotropical butterflies, usually shared by several species in a same locality (currently called mimetic rings), had always attracted the attention of naturalists traveling in the region. Darwin himself was very impressed by the phenomenon, but attributed butterfly color patterns mainly to sexual selection (Darwin, 1871). Bates was the first to relate butterfly color patterns to unpalatability. His theory of mimicry postulates that predators avoid species containing gnauseous smell or tasteh, and a profitable species, usually referred as the gmimich, could obtain protection by resembling an unpalatable one, or gmodelh. The theory also brings the assumption that models are more abundant than mimics, so that predators can meet and learn to avoid them first.
As evidence to support his theory, Bates mentioned first, that presumably unpalatable Ithomiinae, Danainae and Heliconiinae, which he called danaoid and acraeoid Heliconiidae, and presumably palatable Dismorphiinae (Pieridae), often converged in color patterns in a same region, despite a large geographical variation throughout the Amazon valley, and second, that he had never seen a single attack by any of the numerous insectivorous birds of the region on these butterflies, which were usually very frequent, conspicuous and with a slow flight that could make them easy prey.
Some years later, a German naturalist called Fritz Muller working in South-eastern Brazil, proposed that two unpalatable species could also benefit of sharing a similar color pattern (Muller, 1879). Differing from Batesian mimicry, in which the mimic gains its advantage at the expense of the model, and of the predator which it deceives, Mullerian mimicry sought to explain how advantage could be conferred on all species involved, including the predators that could learn more quickly to avoid the unpalatable species (Fisher, 1930). Mimicry theory played a very important part in the early understanding of natural selection theory that, at the turn of the century, was still regarded as a very controversial issue (Fisher, 1930; Owen, 1971).
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