As
we have seen in our Lab portion of Herpetology, bright coloration of an
organism is often associated with either toxicity of the skin, which is seen as
aposematic coloration in poison dart frogs, or as a warning mechanism to
predators that they are venomous, which is seen in species like Micrurus Fulvius, the coral snake. There is a
phenomenon seen in certain species of organisms in which the warning through
coloration mechanism associated with poisonous or venomous organisms is copied
and used with the same intent of protection but lacking the presence of the
danger it warns of. This copying of the coloration is called Batesian mimicry
and this is the primary topic of the article entitled, A Batesian
mimic and its model share color production mechanisms, written by David W. Kikuchi,
David W. Pfennig. This article was published in August of 2012 in Current
Zoology, Volume 58. Issue 4. Essentially, those that use Batesian mimicry are
harmless species of prey and what protects them is the fact that they resemble
its dangerous counterpart, ultimately protecting it. Mimicry can be understood
as convergent evolution within two different species. The ambiguity, in which
this article seeks to clarify, is the actual physiological mechanism from which
this coloration created. If an ancestor has a similar mechanism associated with
the making of the coloration, then this allows for the phenomenon of convergent
evolution that almost seems to have occurred with intent to be explained more
objectively. Because evolution does not occur with a specific intent and is
merely genetically acquired advantageous traits, a ancestral mechanism
consistent with the species allows for this definition to remain in tact. An
example of Batesian mimicry can be seen between a local species of snake in the
family Elapidae, Micrurus fulvius (the
coral snake), and in a species of snake in the family Colubridae, Lampropeltis elapsoides (the scarlet king snake). The poisonous snake is Micrurus fulvius and it has a black nose and is
banded with red to yellow to black and repeats this pattern. The mimic of this
snake is the Lampropeltis elapsoides and
this snake has a red nose and is red then black and then yellow and the pattern
repeats. The phrase that helps keep the patterns straight to determine the
poisonous from the harmless snake is: “Red on Black a friend to Jack, red on
yellow will kill a fellow.” I struggled with the concept of Batesian mimicry
prior to reading this article do to the very concept this article sought to
disentangle, namely, how mimicry evolutionarily came to be since traits are not
created simply because they are advantageous and the organism wants and could
benefit from it. This article shows that the mechanism behind the coloration of
both of these snakes is the same for the two. This leads to the conclusion that
this mechanism was genetically passed down to these two different species by common
ancestor and therefore is not exactly convergent evolution but rather the same evolution
passed on by their common ancestor. The investigators investigated the mechanism by using an Transmission Electron Microscope or TEM to view the skin cells of the snakes and determine composition and other factors associated with pigmentation within the upper-epithelial layers. The histology techniques were extensive and absorbance spectroscopy was used to determine if the tissue samples were similar both species. The consistencies between the snakes were enough to discern the mechanism to be primarily equivalent. This is the website for the article:
2 comments:
Interesting. There are some other examples where the underlying mechanism is conserved, which apparently made a convergent trait easier to evolve.
I almost used this article for my literature synthesis presentation!
I thought it was such a cool topic to study, mainly because coral snake mimicry seems like such a basic concept, but there are so many other factors that play into the mimicry such as the way that the pigments are being perceived by predators, the ratio of the black/red colors, etc.
Post a Comment