Deception and Mimicry

By Branden Holmes (Surroundx) on November 28, 2010

Deception in both the animal and plant kingdoms is one of the most amazing phenomena. Yet the phenomenon is quite easily explained, which betrays the seeming complexity that they present to us: “In the deserts of southern Africa, pebble plants¾also known as ‘living stones’¾blend so perfectly with their stony background that they can be spotted only during their brief flowering season. It is their way of coping with the threat of passing browsers…They are so skilled as mimics that each species is tied to a particular rock formation, imitating its form, colour or texture. Some even reproduce the shine of quartz grains.” (Nature’s Masterpieces, Readers Digest, pg. 90)

Natural selection has the capacity to mould phenotypes to accurately reflect their surroundings. In the case of the living stone plants (Lithops) all that was required for each species was an extended period of time to build up the population numerically. Firstly, the larger a population, the greater the variation that population presents. Secondly, a large number of individuals are required to ensure the survival of the species as it is moulded, otherwise browsers would cause it to go extinct within a short period of time. Individuals that were coincidentally more like the background of rocks that they lived in, were more likely to survive as they were harder to see. Eventually selection by browsers moulded the phenotype to the point where the species were wholly inconspicuous. Another moral which can be derived from the living stone plants is the fact that because they shed their pair of succulent leaves and grow a new pair every year without fail, we can precisely determine how old each individual is. The oldest individuals are more than 200 years old, yet you wouldn’t know it by looking at them because a specimen 1 year old doesn’t look any different from one 200 years old: just because something is tiny it doesn’t mean that it isn’t very old; and just because something is gigantic, it doesn’t mean that it is incredibly old. There is no general correlation between size and age of plants. Treat all of nature with respect. But to get back to the topic at hand, mimicry in animals has stumped many people, no doubt trying to over complicate things. The problem for them is always the same: before the species in question was so thoroughly selected through predators to deceive them by looking like a poisoness counterpart, they must have looked nothing like them. If they didn’t look anything like the mimicked species in the first place how could they have been selected to since they wouldn’t have been mistaken for them? Richard Dawkins in The Blind Watchmaker discusses the problem (pg.’s 81-4) but his solution to the problem hinges on poor vision in predators. I completely disagree with his line of reasoning as to how the resemblance starts, but if you take his explanation as simply how the process perfects mimicry, then I am all for his explanation. Deception. As opposed to mimicry where a harmless species resembles a poisoness one, which aids its survival, deceptive species are coloured red/black/yellow. At the moment I make no distinction between those deceptive species that really are poisoness as those three colours indicate. We could conceivably believe that one or more of these deceptive species’ colour pattern was brought about through sexual selection of males by females; that females of one or more species coincidentally found red/black/yellow or some combination of those colours, to be attractive. The fact that most species so coloured are indeed poisoness suggests some high degree of correlation of pleiotropy. I say high degree as opposed to absolute correlation because not all deceptive species are poisoness. Unlike mimic species which mimic another species (plant or animal), deceptive species which aren’t poisoness mimic a colour pattern (red/black/yellow). Although the distinction isn’t so clear cut, and are better seen as two extremes with many intermediates. The African Monarch Butterflies Tale. The African Monarch Butterfly (Danaus chrysippus), despite its name is found in equatorial Africa, Australia and south-east Asia. But this tale is actually about the caterpillar of the African Monarch Butterfly, which is adorned with the ‘danger’ colours: red, black and yellow on top of a white body, while the butterfly is orange, black and white. The caterpillar, and hence the butterfly, is poisoness as one could guess with a good level of probability by looking at its colouration. But it is poisoness for a different reason than one would initially suspect: it eats toxic plants. That means that its colouration and its toxicity are purely coincidental (so far as we can determine). If other species were found to derive their toxicity from eating poisoness plants, then we would have good grounds (though not absolute grounds) for believing that there must be a subtle correlation between the two.

Related articles:
deception, mimicry

About Branden Holmes
I am an amateur evolutionist interested in the theoretical side of the subject.

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