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Defensive mimicry

In the evolutionary biology, mimicry concerns species who evolves a behavior to mimic another, unrelated species. The behavior can also appear between individuals of the same species.The similarities may apply sound, scent appearance or habitat. A prerequisite for mimicry is that the similarity arises trough an adaptation process.

Usually, mimicry assumes that the mime mimics other species that is dangerous to its own one. That way, the mimic can deter predators. The most common form of mimicry is defensiv mimicry which is used by one species in order to defend itself from another, dangerous species. By imitating the behavior of the predator the mime can avoid the danger. Mimicry is a behavior that appears in almost every animal taxa.

The two main types of mimicry are defensive ones called Bates and Muller’s mimicry. Defensive mimicry is in most cases an advantage of the mime.

Batesian mimicry

Bates mimicry is the most renowned form of mimicry. It assumes that a non-toxic and relatively defenseless specie develops a behavior to imitate a poisonous specie who is capable of defending itself. The type of defensive mimicry was named after the English naturalist Henry Walter Bates. The harmless mimic imitates the behavior of the model to avoid the danger that the model emits. By imitating the behavior of the dangerous species, the submissive specie utilizes the advantages as the model has at no own cost. The imitation can be valid as imitation of example warning colors (strongly yellow, red or black tones). A prerequisite for Batesian mimicry is that the submissive species should be less common than its model species.

The predator species can develop an ability to distinguish the species that naturally utilizes these particular characteristic features from those who imitate them for protection if the behavior appears too regularly. It can also lead to that the behavior develops positive references and in that way result that the specie who originally possess the harmful features gets treated harmless. Some populations of mimics develop the ability to imitate the behavior of several species to gain greater protection from the predators.

The Scarlet Kingsnake

A species who exercises Batesian mimicry is the Scarlet Kingsnake who imitates the aposematism of the Poisonous Coral Snake and therefore sends signals that it is dangerous and toxic which it actually is not. The reason why is because the color combination of the Coral Snake (red, black and yellow) is associated with dangerous signals which The Scarlet Kingsnake has learned to imitate and therefore become able to escape from it's own predators.

Müllerian mimicry

Müllerian mimicry is a form of biological resemblance in which two or more noxious or distasteful organisms, that may or may not be related, exhibit closely similar warning systems. This theory was named after the German naturalist Fritz Müller, who first proposed the concept in 1878. Müller was the one to explain the so-called Bates's paradox. Bates could not find out why this should be so- if both were harmful why did one need to mimic another? It was after observing some butterflies when Bates first find out he could not explain this resemblance. There seemed to be no reason for these unrelated species to be similar, except of that they were all known to be inedible, and their large defence with which to back up the warning coloration, to be similar. Those species have exhibited aposematic warning signals, still there are warning systems such as warning signals and that both share anti-predation attributes, for example being inedible.

Müller consider this theory to be a mimicry, despite the differing from the better known Batesian mimicry (in which one organism is not distasteful) because a predator that has learned to avoid an organism with a given warning system will avoid all similar organisms, thus making the resemblance a protective mechanism.

Two animals that mimics each other forms a Müllerian mimicry pair. Once a pair of Müllerian mimics has formed, other mimics may join them, forming so-called mimicry rings.

Viceroy Butterfly

The Müllerian mimicry was first identified in tropical butterflies. The spices were unrelated, yet there was a resemblance in the warning coloration. The same kind of resemblance is found between the Viceroy and Monarch butterfly. 

These two spices are often hard to tell apart because of their similarity in coloration patterns and display behavior. Both have orange wings, marked by black veins and a black border with two rows of spots. Though that they were long purported to be Batesian mimics, the Viceroy is found to be unpalatable and to some of its predators even more unpalatable than the Monarch Butterfly. The two species resemble one another as a form of defense against predators, forming a pair of Müllerian mimicry.

Most of the predators needs to learn on their own, if a prey is unpalatable or not. Later only the preys with a mutation that moves away from the pattern or behaviour, will be likely to get sampled and damaged by a predator. Thereby the more the butterfly is similar to the coloration pattern the bigger chances it has to survive. Through natural selection the both butterfly species will consenstently move towards the coloration pattern, inherit the good genes and be more and more similar to each other.

Comparison between the Scarlet Kingsnake and the Viceroy Butterfly

Both Batesian And Müllerian mimicry are forms of defensive mimicry. Therefore the Scarlet Kingsnake who practices Batesian mimicry and the Viceroy Butterly who practices Müllerian mimicry imitates other, unrelated species to defend themselves from predators. They imitate the aposematism and the display behavior of other species to benefit themselves with protection since they get associated with the noxious species that they imitate by other outstanding species.

There are also differences between the two types of defensive mimicry. Batesian mimicry assumes that a harmless species imitates another, unrelated harmful species to derive a benefit from the characteristics of the harmful species that signals danger. Müllerian mimicry on the other hand assumes that two or more noxious and unrelated species imitates the behavior of each other to repulse predators. Consequently Batesian mimicry is an advantage only for the mime while in Müllerian mimicry it is a advantage for all the species who evolve to look like one another.

Evolutionary advantages and disadvantages

Batesian mimicry

Animals who possesses the behavior to imitate other species by Batesian mimicry has evolved the ability to defend themselves and avoid harmful species that threats them by having the same aposematism as the harmful species. In that way the submissive species can defend themselves without really having to put a great effort in it. In that meaning Batesian Mimicry is an advantage for the mime who escapes predators and not for the predator who can't separate the harmful species that is not eatable for it from the species who actually is harmless and eatable but seems harmful.

The more the mime can imitate its model, the harder it gets for predators to separate the mime from the model which contributes to the mime getting an even bigger protection. The individuals who imitates the model very similarly gets benefited by a higher protection since it gets harder to tell the mime apart from the model which in turn leads to predators avoiding them. The individuals with the property to imitate the model species very similarly have a higher chance of survival and therefore a higher chance of reproducing and carry on their genes to the next generations who then can take advantage of these characteristic features.

Müllerian mimicry

For the species that practise Müllerian mimicry; the advantage lies in that predators learn from another. Once the predator has learned to avoid the particular coloration pattern or the display behavior of at least one individual -from the mimicry pair or ring- it had its first initial contact with, it will start to avoid all other similarly patterned species. Thereby the species cooparate and does not need to learn every predator on their own.

The initial learning experience of the predator often results in death or damage to the noxious individual that provided the lesson. It is a major loss of individuals for the educating species. Evidence shows that certain predators have little or no inherited recognition at all. In this case each predator needs to learn on their own of noxious or inedible species by sampling them. This means that while the predators are learning, many preys will be harmed by them nevertheless the defensive mimicry. Actually, this is a disadvantage for both sides because the predator will also get harmed if the prey is noxious. The education leads as well to a natural selection where the individual who has the least similar color pattern or a mutation that moves away from the coloration pattern, will extinct first. It is a disadvantage for those individuals although a advantage for the species, that stays cleaner. The biggest advantages gets the species that join the mimicry ring after the educatings of the predators are finished. The new members do not have to sacrifice themselves to learn the same predator.