The year was 1848. a young British naturalist named Henry Walter Bates had gone to the Amazon with fellow countryman Alfred Russel Wallace to look for evidence of the origin of species. Over the course of his 11-year stay, he noticed that local relatives of a European butterfly known as the cabbage white—the pierids—were bedecked in the showy reds and yellows of rain forest butterflies called heliconids. Observing that the heliconids seemed to possess toxins that made them unpalatable to predators, Bates reasoned that by mimicking the toxic heliconids’ warning colors, the harmless pierids were escaping predation. When Bates returned to England in 1859, the year that Charles Darwin published On the Origin of Species, his discovery of these “mockers,” as he called them, became the first independent evidence to corroborate Darwin’s theory of evolution by natural selection—which holds that organisms best able to meet the challenges in their environment survive to produce the most offspring, so that their traits become increasingly common through the generations.

Apart from Darwin and Bates, though, most biologists were slow to recognize the significance of nature’s impersonators. But now, a century and a half later, mimicry is fast becoming a model system for studying evolution. It is ideally suited to this task because both the selection pressure (predation) and the traits under selection are clear. Indeed, mimicry demonstrates the process of evolution in its most stripped-down form. Discovery of new types of mimicry has also helped fuel fresh interest in the phenomenon among biologists. Joining the classic examples familiar from high school biology class—such as the scarlet kingsnake, whose coloring resembles that of the eastern coral snake, or the viceroy butterfly, whose wing pattern matches the monarch’s—are chemical, acoustic and even behavioral mimics. And stunningly, genetic analyses of one group of mimics have revealed a mechanism by which new species can arise.

This article was originally published with the title Masters of Disguise.

3 Comments

1. 1. kdonald 03:32 PM 5/13/11

   Before anything is said, considering how rousing this topic can be, I just want it to be known that I am in agreement with a good majority of evolutionary theory. It is just that I think we could all do well with a healthy dose of incredulity when biology has not advanced so far as to say that everything within its branch of study is without any mystery. We know a great deal about organic life, but I am reluctant to say (as Huxley has said in the past) that we know all of the fundamentals and that there is only need for the minor details to be filled in.
   
   That being said, I know that I can move my arms at will, but I can't seem to change my biology at will. I agree that natural selection plays a large role in evolution (and I would even be willing to accept that it may be the only role if I only knew more), but I am left wondering how or even why an organism would be able to mimic another's form in its totality. Perhaps the organism is able to recognize that some other form is more suited to its environment, but even with incremental proof of change, I am still left wondering about the cause and effect of change at the creative level.
   
   Granted, genetic drift may not need a cause, being always active, but I am concerned about hopeful monsters and their frequency -- sometimes being necessary to combat predation and sometimes not -- since large scale changes seem infrequent. With this in mind, speciation seems slightly problematic to me, but all of this does not mean that I do not admire the elegance and explanatory power of natural selection. I just feel as though more legwork needs to be done to explain changes that are more than skin deep (but this may also mean my own legwork). Can we say that it is genetic ingenuity that caused the tiger moths to click, or the caterpillar to take up chemical and acoustic signals all on their own. I would like to spend time on these things if I was a specialist, but I am not. I am left wondering about the creativity of these organisms and just where that creativity comes from (origin of discovery if you like) since it seems as though some ingenuity on the part of the subject is necessary. Lamarck?
   
   I am willing to admit that I am far from being as proficient in these things as I would like to be. Even with our profound knowledge base I am also willing to accept that some things still need explanation. I mean it sounds very silly for someone to argue that all of life was created 2000 years ago, but perhaps it is worthwhile to allow room for legitimate criticism when some mystery still abounds.

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2. 2. Bill Crofut 04:34 PM 5/13/11

   If "mockers" was indeed, "...the first independent evidence to corroborate Darwin’s theory of evolution by natural selection..." why was Prof. W. R. Thompson, FRS
   unaware?:
   
   "The view that natural selection, leading to the survival of the fittest, in populations of individuals of varying characteristics and competing amongst themselves, has produced in the course of geological time gradual transformations leading from a simple primitive organism to the highest forms of life, without the intervention of any directive agency or force, is thus the essence of the Darwinian position....That natural selection directs the course of evolution Darwin could not prove by an appeal
   to facts."
   
   [1956. Introduction. In: Charles Darwin. Origin of Species. Everyman Library No. 811. London: J. M. Dent and Sons. Reprinted with permission. Evolution Protest Movement. 1967. NEW CHALLENGING ‘INTRODUCTION' TO THE ORIGIN OF SPECIES. Selsey, Sussex: Selsey Press Ltd., pp. 6, 7]

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3. 3. HdeJong 08:40 AM 5/31/11

   I've read the paper version and was amazed by a proposed mechanism for speciation:
   "The gene for wingcolor in Heliconus is inherited with the gene for mate choice. That link accounts for the instant preference the artificial hybrid butterflies showed for their doppelgängers. This relation between wing color and mate choice provides a mechanism by which speciation can occur." Say I'm a butterfly with black and white parents, but I happen to be purple. I think my coupled mate-choice gene then tells me to fall in love with a black and white moth of the opposite sex. Or must I believe this mutation tells my matechoice gene to tell me to love purple moths? Or does it tell me to inspect the colors of my own wings and love only somemoth like me? I'm too confused to make a choice.
   Or do these genecombinations already exist in the genepool, but then it's not a real "mutant", is it?

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