The Origin of Mimicry Theory

Henry Walter Bates

“Every species in nature may be looked upon as maintaining its existence by virtue of some endowment enabling it to withstand the host of adverse circumstances by which it is surrounded. The means are of endless diversity. Some are provided with special organs of offence, others have passive means of holding their own in the battle of life...A great number have means of concealment from their enemies, of one sort or other. Many are enabled to escape extermination, or obtain subsistence, by disguises of various kinds; amongst these must be reckoned the adaptive resemblance of an otherwise defenceless species to one whose flourishing race shows that it enjoys peculiar advantages.”

- H.W. Bates, 1862

I start here with another great quote by Henry Water Bates. He was a naturalist who travelled with Alfred Russel Wallace to South America. You can read about his travels and experiences in his book “Naturalist on the river Amazons”. An amazing naturalist and great thinker he developed the theory of what is now called Batesian mimicry. In particular, he provided the theoretical foundation for how the mimics he observed might evolve. Although maybe not fully appreciated at the time his work captured the interest of Darwin who wrote:

"I have just finished after several reads your Paper. In my opinion it is one of the most remarkable & admirable papers I ever read in my life. The mimetic cases are truly marvellous & you connect excellently a host of analogous facts…I rejoice that I passed over whole subject in the Origin, for I should have made a precious mess of it. You have most clearly stated & solved a wonderful problem.”

Darwin goes on to say: 

“With respect to mimetic resemblance being so common with insects; do you not think it may be connected with their small size; they cannot defend themselves;— they cannot escape by flight at least from Birds; therefore they escape by trickery & deception?

I have one serious criticism to make & that is about title of paper; I cannot but think that you ought to have called prominent attention in it to the mimetic resemblances.—Your paper is too good to be largely appreciated by the mob of naturalists without souls; but rely on it, that it will have lasting value, & I cordially congratulate you on your first great work. You will find, I sh^d. think, that Wallace will fully appreciate it.”

See the full letter from Darwin here: http://www.darwinproject.ac.uk/entry-3816

Darwin was clearly impressed and saw the lasting value of Bates’ work. It’s a bit hard to find the manuscript but anyone seriously interested in mimicry should take a read:

• Bates HW (1862) Contributions to an insect fauna of the Amazon valley. Lepidoptera: Heliconidae.  Transactions of the Linnean Society of London 23:495-566

You can’t help but agree with Darwin about the title of Bates paper. Darwin's comments raise a few interesting and particularly relevant points to my project. Caterpillars, especially large ones, are under intense selection to avoid predation by birds. Caterpillars can’t outrun their attackers, and just dropping off their host plant might have serious consequences. Many caterpillars can only eat one plant species and there are a whole suite of different enemies on the ground like ants that could make short work of a caterpillar. So those caterpillars with a different solution - such as the mimetic resemblance to a dangerous snake - survive to breed as adult butterflies or moths.