The Evolution of the Peppered Moth

The evolution of an organism develops owing to the changing nature of its natural environment over time. Melanism is one of the aspects caused by industrial development in England, which has brought about complex historical and geographical alterations of peppered moth’s behaviors and survival attributes (Gupta et al. 2017, 492; Hancock 2006, p. 193). The concept of evolution is a distinguished academic revolution in the history of humankind progressively transforming the perception of people about the world. Charles Darwin postulated a consistent philosophy of evolution after accumulating a wealth of information and knowledge. Darwin’s evolution theory encompasses three fundamental ideas, which include, species changing over time and space, changes caused by evolution are slow and gradual and all organisms have a shared ancestor with one another. Evolution by natural selection was another concept supporting Darwin’s theory. The system is an elegant and logical approach to explain how populations can evolve in such a manner that they become more adapted to their surrounding over time (Fabio Zampieri 2009, p. 334; Sarkar 2017, p. 754). Darwin based his theory on various observations, which included heritable traits, not all offspring produced can survive, and descendants have varying heritable traits. These essential interpretations have helped build concepts and ideas that support the notion of natural selection and evolution of living creatures.

Natural selection refers to the mechanism, which causes the evolution of an organism when its environment fluctuations. According to the concept, the battle for resources in the community will favor some people or species of animals with superior traits (Doolittle 2017, p. 276). As a result, over time the frequency of traits within the community changes considerably to increase the chances of survival for the best-suited species of animals. The qualities that make one organism to have an advantage over the others is called adaptation. Based on Charles Darwin’s observation, for natural selection to function on characteristics of an organism, the traits must have variations that are heritable and demonstrate some advantages in the competition for resources in the community (Kull 2014, p. 287; Susan et al. 2011, p. 208). In case one of the requirements does not happen, then a trait has not experienced natural selection. The system occurs through a comparative advantage and not absolute standard of a scheme.

Industrialization in England considerably played a role in the evolution and natural selection of the melanic trait to make the organism more adaptable to the surrounding over time. During the era, atmospheric pollution, food abundance, and the number of predators substantially varied hence increasing the evolution of particular traits in some creatures especially the peppered moth. The changing color of peppered moths in polluted regions enabled them to camouflage and hide from the predators. The characteristic enhanced their survival ability in the forests where several predators existed. The moths that possessed the quality of camouflaging remained suited for the struggle for the scarce resources in the ecosystem as well as producing more descendants to the next generation. Consequently, the report will focus on critical analysis of peppered moth evolution during the industrial revolution in England. In the process, explain the process by which the organism has become adapted to its environment as well as how its environment has changed over time. Finally, the report will provide concluding remarks regarding the knowledge and information collected on the topic.

Genetic code

Genetic code refers to a sequence nucleotides in ribonucleic (RNA) and deoxyribonucleic (DNA), which defines the arrangement of amino acids. Although the linear organization of nucleotides in DNA have the information for protein synthesis, proteins do not come from the DNA directly (Rapacioli, Rofman, and Flores 2006, p. 08). Some of the important rules governing the genetic code degeneration include:

i. Any BB- that has C is a non-discriminating with an exception of when B2 is A. However, any BB- with A is selective except when B2 is C.

ii. Y remains a non-discriminating material and R is a selective property

iii. Any BB- with bases in first and second position possessing the property 3 is considered non-discriminating and any BB- with bases in first and second position demonstrate the property 2 as discriminating.

iv. 3 is a non-discriminating material and 2 is a selective property.

Properties of genetic code

Genetic code demonstrates some essential properties that help the DNA to function accurately. These include:

i. The genetic code is triplet meaning it has approximately 64 codons that are adequate to make 20 amino acids.

ii. The code is universal meaning that same amino acids are assigned to similar codons.

iii. Genetic code is commaless meaning the codes have no demarcation lines between them.

iv. The genetic code do not overlap

v. The code is non-ambiguous

vi. Genetic code have polarity meaning it has a definite direction considered for reading messages.

Mutation refers to the errors that occur in codons caused by alterations in nucleotide bases. Even though mutations cause an adverse effect on the organism, some may bring no impression on the organism. Some of the mutations include:

Missense mutation: This refers to the modification that results in the changing of DNA base pair leading to the substitution of an amino acid for another in the protein. Missense mutation alters the polypeptide hence can adjust the whole protein’s function in the DNA.

Nonsense mutation: The transformation causes the change in a DNA base pair. However, instead of exchanging an amino acid for another, the modified sequence of DNA prematurely sends a signal to the cell not to synthesize protein. The mutation causes the shortening of proteins, which may not function appropriately or not at all. Therefore, it leads to the early termination of a polypeptide.

Insertion mutation causes alterations in the number of DNA bases in a gene by adding a particular DNA piece. Therefore, a protein made by these modified genes may not function correctly.

Deletion mutation: This causes a change in the number of DNA bases by eradicating a DNA piece. Small omissions may cause the removal of one or a few base sets within a gene while larger ones may eliminate the whole gene or some nearby genes.

Mutation can either be beneficial, harmful or neutral. However, metamorphoses do not supply what an animal needs. Factors within the environment influence the frequency of random mutation but do not guide the direction of the process (Russell and Beckenbach 2008, p. 682). For instance, in the UK some people use shampoo containing compounds that kill lice. Nevertheless, the persistent use of these chemicals has witnessed the emergence of new species of lice with new adaptation traits that are resistant to the shampoo chemicals (Hafeez, Khan and Qadir 2014, p. 945). Therefore, the variations within a given population make it possible for the population to change over time in response to the environmental changes, which naturally select the well-adapted alleles. The new species that emerged passed the alleles to their offspring and to the next generation to boost their survival and competition for foods and camouflaging for defense.

Fig. 1.0: showing the non-resistant and resistant lice

The Peppered Moth of England

The Peppered Moth is a widespread insect in Britain and Ireland and often discovered in ordinary backyards. The story regarding the animal is a classic example of how natural selection works to make well-adapted creatures to survive in the environment. During the industrial revolution, scientists noticed that white moths were becoming rare while their black counterparts were common. As a result, the phenomenon has remained to be a case of industrial melanism owing to the blackening smoke produced during the era in England. A typical moth has a scattering black marks on a clear background. Scholars have revealed that a chain of dominant alleles at a single location determined the melanic forms (Carbonara and transitional Insularia) during the epoch to aid their camouflaging traits. However, in the case of the peppered moth, their number extremely increased that in some regions of London the original species had almost disappeared by the end of the 19th century. The evolution that resulted in increasing number of the peppered moth in England is called industrial melanism and hence exemplifying the perception of Darwin’s theory of evolution. The species demonstrated phenotypic variations (light and dark forms) that supported the natural selection during the industrial revolution. In this case, predators especially birds fed on conspicuous moths. Nevertheless, because the background colouring adjustments, the population of the organism evolved fast to survive the constantly changing environment (Cook and Saccheri 2013, p. 207). The reduction in the number of lichen covering forest trees owing to the increased environmental pollution by industries in forests and nearby urban centres has remained to be the major factor that enhanced Peppered Moth’s evolution. Lichens made the light form more exposed while the dark form camouflaged in the environment. Therefore, birds often ate the light-colored Moths because of their visibility when they perch on darkened trees during the day leading to a decrease in population of the organism (Holdrege 1999, p. 66). The dark-colored moths had a higher survival rate compared to their counterparts as they lived longer passing the genes for the dark color to their offspring.  Industrialisation created an environment that naturally selected the dark coloured individuals hence they became successful after the changed appearance of the trees and forests.

Fig 1.1: white form of peppered moth

Fig 1.2: Melanic form peppered moth

However, more observations have brought a significant difference to the ecosystem after the situation started reversing in the 1950s. Since the government of England introduced the Clean Air Act various sectors have developed advanced technology as well as clean fuels, which have considerably reduced the level of pollution in regions occupied by Peppered Moth. The development has witnessed an increased growth of lichens again; therefore is no soot to cover bark of the trees. As a result, the population of light peppered moth has substantially grown in the region as it can better camouflage in the surrounding. The development in the environment has observed the phenomenon of natural selection on both sides often favoring the moth that best fits within the existing environmental condition. Unfortunately, after adapting well to survive the extreme condition of the industrialisation that eliminated other species, its population is currently declining.  According to Darwin’s theory, the ecosystem during and after industrialisation acted as the selecting agent in natural selection by considerably eliminating one species of moth while aggravating the population of another (William Beachly 2010, p. 104). However, the phenomenon of natural selection took short period, unlike the Darwin’s postulated time span. The random genetic alterations in moths resulted in the emergence of peppered moths during industrialisation in England. As a result, the peppered moths became better suited to survive in the environment when trees were darkened leaving the light moths with low chances of surviving. These organisms had more offspring leading to a population explosion among peppered moths during industrialisation. In later generations, the organisms experienced more genetic alterations making them better fit to survive in England after the industrial revolution. Some of the aspects of making a natural selection of peppered moth possible are behavioral and physical changes, which transpire at the DNA level and genes. Such as alterations result in mutation, a process that allowed the evolution of these organisms to take place during the industrial revolution leading to high population. A random mutation in peppered moth was neutral thus being beneficial to the species improving their probability of surviving and breeding.

Conclusion

The theory proposed by Charles Darwin has changed the perception of humans as well as scholars on how environment plays a considerable role in eliminating organism that is not well-suited to survive. The report has drawn three major conclusions regarding the research on natural selection. These include; (i) adaptation of an organism in their natural environment takes a period, (ii) organisms that do not have survival traits become eliminated through a process of natural selection and (iii) evolution of a new species takes place at the genetic levels affecting the arrangement of the genes to come up with a mutant. Mutation is one of the processes that has considerably supported the evolution of organisms within their ecosystem. If random mutation would not have occurred the species would become extinct because they become vulnerable to predation. Birds would constantly feed on them because of the visibility when the perch on the bark of the trees. The resulting effect would cause an imbalance to the ecosystem as birds would feed on all of them leading reduction in the number of birds as well as animal preying on birds.

References

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