Survival of the Fittest: Monarch and Viceroy Butterflies

By: Chris Frey, Griffin Murphy, Jason Shah, Mick McColl

Darwin’s Theory of Evolution was a groundbreaking advancement, explaining how natural selection results in the inherited biological change within a population. This is evolution. Biological fitness is central to this theory, and although many people understand that the fittest survive, not all understand what this truly means.  Biological fitness is measured by the ability of an organism to reproduce and successfully pass on its genes to future generations. Misconceptions arise when individuals perceive the largest, strongest organisms within a population to be the most biologically fit. To demonstrate fitness in the context of evolution, one need only look at butterflies.  They come in all shapes, sizes and colors, sometimes adopting another species’ physical characteristics in a process known as mimicry.  Mimicry comes in several varieties, including Batesian mimicry, which is when a palatable organism mimics a species that is unpalatable to predators. Consequently, they are avoided by predators, increasing their fitness.

A vivid example of Batesian mimicry is depicted by Viceroy and Monarch Butterflies. Monarch butterflies are unpalatable due to toxic milkweeds they consume as larvae, which results in low levels of predation in their natural environment.  Viceroy butterflies have wings emblazoned with similar shape and color schemes, ostensibly reducing the predation rate. Colors must be matched very closely as avian predators have some of the most developed eyes in the animal kingdom (for more information, see paper from 2012 by Stoddard and colleagues listed below).

A vivid example of Batesian mimicry is depicted by Viceroy and Monarch Butterflies. Monarch butterflies are unpalatable due to milkweed they consume as larvae, which results in low levels of predation in their natural environment.  Viceroy butterflies have wings emblazoned with similar color schemes, ostensibly reducing the predation rate. Wing shape plays an important role in mimicry too (for more information, see paper from 2013 by Jones and colleagues listed below).

Monarch and Viceroy butterflies serve as a model organism for mimicry and the evolutionary concept of survival of the fitness. Similar mimicry models have been recently exposed within a microbiological context. A bacterial pathogen has been discovered that mimics the structure of some of its intended hosts’ carbohydrates. This structural mirroring results in a reduced innate immune response by the host (for more information, see paper from 2009 by Carlin and colleagues listed below). In essence, the bacterium mimics the structure of the host species in order avoid immune detection and thus increase its chance of survival.

A visual explanation of Monarch and Viceroy mimicry has been provided below:

 

In addition, listed below are some articles on mimicry

Carlin, Aaron, et, al. 2009. Molecular mimicry of host sialylated glycans allows a bacteria pathogen to engage neutrophil Siglec-9 and dampen the innate immune response. Blood Journal. 2009.

Holmes, B. 2010. Accidental evolution: the real origin of species. New Scientist 205: 30-33.

Jones, R.T. 2013. Wing shape variation associated with mimicry in butterflies.        Evolution 67: 2323-2334.

Matthews, E.G.  1977. Signal-Based frequency-dependent defense      strategies and the evolution of mimicry. The American Naturalist 111: 213-222.

Rowe, C. C. Halpin. 2013. Why are warning displays multimodal. Behavioral Ecology and Sociobiology 67: 1425-1439.

Stoddard, M.C. 2012. Mimicry and masquerade from the avian visual perspective. Current Zoology 58: 630-648.

Williamson B.G., C.E. Nelson. 1972. Fitness set analysis of mimetic adaptive strategies. The American Naturalist 106: 525-535.

Yahner, R.H. 2012. Additional adaptations against predation. Wildlife Behavior and Conservation 55-64.

 

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