Müllerian mimicry. Müllerian mimicry was first identified

Müllerian mimicry is a form of biological
resemblance in which two or more dangerous or toxic organisms exhibit similar
warning systems. These organisms, that may or may not be closely related, facilitate
predator learning by mimicking each other’s warning signals, such as the same brightly colored wing
pattern, to their mutual benefit. Because a predator that has
learned to avoid an organism with a given warning system will avoid
all similar organisms, the resemblance between Müllerian mimics acts as a
protective mechanism for participating organisms. Through a variety of
technical approaches in developmental genetics and the construction of genetic
linkage maps, researchers determine gene expression and selective agents as sites
that controls phenotypic traits related to mimicry.

            Müllerian
mimicry relies on aposematism, or warning signals that make harmful
organisms more identifiable by predators. Organisms with these signals are
avoided by predators, which learn through experience not to hunt the same unpalatable
prey again.           Researchers
speculated that noxious organisms that developed a resemblance to each other may
have had a selective advantage over organisms with unique warning signals. If different prey species with a mutual predator
employed their own distinct warning signal predators would have to learn to
identify several different unpalatable prey groups through experience. Unalike
prey groups would suffer a greater loss of individuals due to the increased
number of learning experiences required for predators to learn each warning
signal. Prey that evolve to share a similar appearance or mannerism share the
costs of predator education and reduce the overall number of experiences
required for predators to learn a common warning signal. Because prey species
that appear similar to unpalatable species often escape predation in
comparison to their conspecifics, natural selection drives prey
species toward a single warning language. This mutualistic arrangement subsequently
leads to multiple species joining the protective cooperative and the evolution
of Müllerian mimicry.

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            Müllerian mimicry was first
identified in tropical butterflies that shared colorful wing patterns.

Some insight into the evolution of mimetic color mimicry in longwing (Heliconius) butterflies
in particular can be seen through the study of the genes associated with color
patterns in wings. The butterflies’ signature red wing patterns, which signal
to predators of its toxicity, is largely controlled by the Optix gene. By
sharing this distinct coloration pattern Heliconius butterfly increases its
chance of survival through association with other poisonous red winged
butterflies the predator may have previously established as unpalatable. The
genetic linkage maps of many related species of Heliconius butterflies
show that the evolution of a single transcription factor (Optix gene) plays a
crucial role in driving the convergent evolution of composite color patterns in
distantly related species. Because the hypothesized reason behind phenotypic mimic
traits is the evolution of a non-coding piece of DNA that regulates
the transcription of nearby genes it is difficult to determine if the trait
is homologous or simply the result of convergent evolution.

However, the results of previously complied studies revealed that an allelic substitution
at the Optix locus in the Numata longwing butterfly (H. numata) and in the postman butterfly (H. melpomene) showed no obvious phenotypic homology.

            One proposed mechanism for Müllerian
mimicry is the “two step hypothesis”. The hypothesis consists of an initial
mutational leap that establishes an imprecise resemblance of the mimic to the
model, followed by smaller changes establish a more accurate semblance. However,
the two-step process relies on the assumption that a mimic trait is governed by
a single gene, which is unlikely given the complexity of the coloration
patterns observed in Müllerian mimics. A simulation of a model population was
compared to a mimic population on a feature trait scale and determined that without
an initial mutational leap toward likeness in phenotype, a similar simulation
did not result in gradual mimicry evolution in the mimic population. The
researchers concluded that drastic changes in qualities used by predators to determine
palatability of prey would likely be essential in the initiation of Mu?llerian mimicry
evolution. The implications of this conclusion suggest that the evolutionary
path to mimicry becomes more likely when the mimic population has a
predisposition to be similar to the model population.

 

Müllerian
mimicry, advergence may be more common than convergence. In advergent
evolution, the mimicking species responds to predation by coming to resemble the
model more and more closely. Any initial benefit is thus to the mimic, and
there is no implied mutualism, as there would be with Müller’s original
convergence theory. However, once model and mimic have become closely similar,
some degree of mutual protection becomes likely. This theory would predict that
all mimicking species in an area should converge on a single pattern of
coloration. This does not appear to happen in nature, however, as Heliconius butterflies
form multiple Müllerian mimicry rings in a single geographical area. The
finding implies that additional evolutionary forces are probably at work

theorized that
all of these insects gained protection by displaying the same warning colors.

Should a predator eat one insect with a certain coloration and find it
inedible, it would learn to avoid catching any insects with similar coloration.

Mullerian mimicry is where a set of different protected species adopt similar
colorings to show potential predators that it is protected. In the example, we
saw stinging insects displaying a similar color.