Abstract
The red squirrel is one of the modern wonders of evolution. The squirrel has a surprisingly red toned fur as opposed to the conventional grey squirrels. The red pigmentation of the fur of this squirrel can be attributed to a process known as melanism. This is the process through which darker pigmentation occurs. This dark pigmentation can be expressed either in skin or in feathers or in fur. There are a number of factors leading to the development of the red squirrel for example habitat. The red squirrel lives in Europe and primarily in Denmark. The squirrel also lives on top of trees and carries out most of its habitual activities on the trees. These trees have barks which have a red ppigmentatiion.as a result of the red pigmentation on the barks of the trees the fur of the red squirrel also developed its red pigmentation. This is known as adaptive melanism as it involves melanism occurring so as to enable the squirrel too fit perfectly into its habitat. The melanism of the squirrel however goes further than habitual factors. The habitat only acts as a catalyst for the melanism but the actual melanism is a genetic process that involves mutation in the DNA of the squirrel.
Genetics of melanism in the red squirrel
The red squirrel is a species f squirrel that lived mainly in northern Europe and especially in Denmark. The red squirrel is a tree squirrel and could be found mainly on trees. The red squirrel has been driven to near extinction leading to the need of preservation of this red squirrel. The following essay examines the red squirrel.it examines the red squirrel with reference to genetics. The essay delves deep into the genetic coding that leads to the development of the red pigmentation in the red squirrel and why this pigmentation occurred particularly in the red squirrel taking into account that there are also black squirrels as well as grey squirrels. The hypothesis is that there are a number of genetic and evolutionary factsors in play as far as pigmentation is concerned. The following is a research proposal to establish the causes of the red pigmentation in the red squirrel
The methods for this research involve analysis and research of literature on the red squirrel. Observation will be used as a method of data collection on the red squirrel. The timeline for the completion of the research is approximately three weeks. This time period is sufficient to collect enough information on the red squirrel.
Analysis of the theoretical aspects.
In order to understand the genetics behind the manifestation of the red pigmentation in the red squirrel it is first very important to understand the concept of melanism. Melanism is the process by which a darker pigmentation occurs. Melanism is in other words the exact opposite of albinism. Melanism leads to manifestation of dark pigmentation and this in turn leads to development of a darker tone. Melanism is not only limited to the animal kingdom. Even human beings experience or rather undergo melanism.an example is that of people living in Africa. Their skin has a darker tone in comparison to the people living in Europe or the Americas. This is a perfect example of the embodiment of melanism, melanism at work in other words. There are several types of melanism or rather several processes that lead to melanism (Silva,23). The important process leading to melanism as far as this study is concerned is adaptive melanism. Adaptive melanism is the process by which the intonation of an organism gets darker as a means to enable the organism to adapt better to the particular environment in which it lives. This adaptive melanism can occur as a means of camouflage and stealth r even as a means of intimidation and animal dominance.an example of melanism for intimidation and dominance is the Black Panther. True the melanism in the Black Panther also helps the Black Panther to be virtually impossible to see in the dark thus making it a more effective hunter especially at night. The melanism in the Black Panther is however more inclined towards intimidation than it is towards camouflage and effective hiding. The red squirrel underwent a type of melanism that gave it a red pigmentation.
Environment of the red squirrel
Before delving into the exact mechanics of how all this happened it is very important to understand what triggered melanism in the red squirrel. This can only be done through detailed analysis of the environment in which the red squirrel lived.as stated the red squirrel lived primarily in Europe and especially in Denmark. The red squirrel just so happens to be a tree squirrel. The trees in northern Europe and especially in Denmark are peculiar looking in that they have barks that are reddish in color. From a distance these trees appear completely red and are very beautiful to say the least. With the red squirrel living in this habitat it thus logically followed that the squirrel had to fit into this habitat (Kettlewell, 51). The squirrel had to blend into the habitat in order to ensure continued survival of the species and better adaptation into the environment. This environment therefore stimulated the melanism in the red squirrel which led to the red squirrel developing a red pigmentation. The red pigmentation in the red squirrel is therefore a form of adaptive melanism. This melanism occurred so as to enable the red squirrel to be able to live in its environment with a degree of camouflage. This camouflage is very necessary in preserving the species because it ensures that the squirrel is not directly visible to would be predators. The predators have to take a harder look in order to determine the exact location of the red squirrel in its environment.
Research findings
The development of the melanism in the red squirrel leading to the development of the red pigmentation can be attributed to genetics. This genetics is coupled with a wide range of mutations and the result is a red squirrel. The squirrel just so happens to be a mammal.in order to understand evolution and mutation in the red squirrel it is very important to have a general picture of evolution and mutation in all mammals in general since they all share some similarities and there are certain aspects that are in all mammals and transcend the boundaries of genus and species. Studies have shown that the DNA of mammals is capable of evolving five to ten folds more rapidly and faster than than single copy nuclear DNA. Mutations in mammals occur in terms of base pair modifications and in certain cases replacements (Kettlewell, 108). In mammals however mutations can occur in in single or even multiple modifications and in some cases replacements. There are various functional regions as far as the DNA of mammals is concerned. These functional regions evolve at different rates. This is to say that each functional spot associated with the DNA of mammals evolves at a different rate and a different pace from other functional spots in the very same DNA of mammals. There are therefore hot spots for mutation. These hot spots for mutation are areas in DNA where mutations are most likely to occur. These are the areas where in most cases mutation does occur with the greatest of ease and at a rather high frequency. The surprising thing about these hot spots for mutation is that they can occur even in non-coding areas of the DNA. Non coding areas are areas that are generally of low significance as far as the traits of the organism are concerned. These are areas of little emphasis and play very little roles in the development of traits in the organism be they hereditary or otherwise.
Analysis of findings
There is a very large number of loci that have been linked with the pigmentation that normally occurs inn vertebrates. These loci are well above a hundred. Melanin is however the most studied in terms of comprehensive analysis and exhaustive investigations and it has been determined that melanin bases pigmentation is very common especially in vertebrates of which the red squirrel just so happens to be. Melancolytes are purely responsible for the production of melanin through a process known as melaniogenesis. These specialized cells are responsible for the production of the different types of pigmentation which occur and are clearly visible in a very large number of vertebrates and in some instances even invertebrates. These pigment types produced by the specialized cells are however regulated and distributed in different ways. These trends in terms of regulation and distribution of the pigment types are purely responsible for instances where some vertebrates appear to have a different pigmentation from another vertebrate yet they all belong to the same species. Such is the case with the red squirrel which has a different color from the black squirrel which also in turn has a different color from the grey squirrel. The melancolytes found in mammals are capable of synthesizing two forms or rather types of melanin. These two forms of melanin associated with mammals are phenomelanin and eumelanin. These two forms of melanin are very different in terms of the traits that occur as a result of their presence or rather their dominance. When eumelanin is produced and becomes dominant it results in pigmentation ranging from dark brown too black. This pigmentation is especially dominant and very visible in feathers, in hair and in skin. Phenomelanin is however very different from eumelanin (Sanderson, 213). Phenomelanin results into a pigmentation that ranges from red to yellow. When produced inn excess amounts or when synthesis fails to take place phenoomelanin leads to albinism. Both phenomelanin and eumelanin are produced in vertebrates but their interaction and eventual dominance is regulated. Extension locus E is responsible for the regulation of the interaction between the two types of melanin produced in vertebrates and especially mammals. Extension locus E is responsible for the encoding of the cell surface protein melancortin1receptor or MC1R.MC1R is especially expressed in melancocytes and especially in the agouti locus encoding agouti signaling proteins. The MC1R is a G‐ protein coupled receptor and the activation of this 7‐ trans membrane domain receptor by the binding of its receptor ligands results in a signaling pathway which ultimately leads to the production of eumelanin or phaeomelanin. The agonist alpha melancocyte stimulating hormone is purely responsible for the activation of the MC1R. There is also a competing enzyme known as the antagonist ASIP which also serves to activate the MC1R. The difference between these two competing enzymes is that the agonist alpha melancolyte stimulating hormone leads to the production of eumelanin while the antagonist ASIP leads to the production of phenomelanin. If the competing receptor antagonist Agouti ASIP binds to MC1R the agonist mediated response is blocked or reduced. The intracellular levels of cAMP are repressed by the aid of the extracellular protein Atrn. By affecting intracellular levels of cAMP the catalytic effect of the enzymes involved in the eumelanin pathway are affected and the synthesis is switched to phaeomelanin. The synthesis of phaeomelanin depends on the incorporation of cysteine which is regulated by xCT. The interaction that therefore occurs between these two proteins and this interaction is very important in the regulation of melanogenesis and also the switch that occurs between the production of either phenomelanin or eumelanin. The variation seen in fur and coats of animals is therefore as a result of the distribution of these two pigments. The amounts of these two pigments is also very important especially in terms of the intensity of the color manifestation. This therefore explains how the red squirrel is able to develop the red pigmentation as well as how the black and the grey squirrel are able to develop the black pigmentation and the grey pigmentation respectively. Since these trends in pigmentation are hereditary they were passed on to the next generations.
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