This paper gives an explanation of Darwin’s theory of natural selection. As well, the paper fully gives a description of natural selection in terms of “modern evolutionary synthesis” of the 20th century. The paper also gives application of the principles of natural selection to explain the current problem of antibiotics resistance in bacteria. Finally the paper gives a summary of scientific theories about evolution before Darwin’s discovery of natural selection.
Generally this is a very important theory which has been greatly adopted by students and teachers of genetics presently.
Introduction
Summary of Scientific Theories about Evolution before Darwin’s Discovery of Natural Selection
Description Of How The Discovery Was Made By Darwin.
Natural Selection In Terms Of the “Modern Evolutionary Synthesis” Of the 20th Century
Natural Selection and Its Relationship to Antibiotic Resistance in Bacteria
Conclusion
Charles Darwin is known to be the father of evolution and heredity and came up with principles that govern heredity. His one outstanding principle is that of natural selection that dictates that if evolution was elucidated as a car, and then the theory of natural selection would be its engine.
The theory categorically states that it’s the nature that controls and select organisms, which tend to have favorable characteristics for survival while at the same eliminating species that are inferior (Fairfield, 2000).
Darwin’s theory is significantly a very important landmark in the process of evolution and origin of species. The principle is regarded as the key to the formation of new and superior species from old and existing ones.
This is to say that nature selects superior traits, which are transmitted to the offspring in a manner that is independent on the other. The major explanation behind the theory is that one superior allele tends to be dominant over the others, blending a genetic make up and traits that influence a certain trait segregate during organism growth and development. Therefore, this research paper looks at all principles of natural selection, its relationship to the current problem of antibiotics resistance in bacteria, and its description in terms of “modern evolutionary synthesis” of the 20th century.
Darwin’s theory of Natural Selection is generally regarded as a significant landmark in the origin of organisms and evolution process. Before Darwin, many scientists like him alleged that species evolved from other species or antecedent. Mostly during those times there was no any scientific evidence to prove that concept hence many theories went unnoticed. Prior to Darwin’s theory especially in medieval times, the concept of evolution was not much appreciated for the reason that origin of organisms was regarded as Gods creation. This idea claimed that organisms came into existence in a way that they were unchanged, hence going against the notion of evolution.
Many scientists like Immanuel Kant established a notion of descent that was close to modern view; were he suspected that organisms may have originated from a common ancestor .His analysis emerged from studies of Orang Utang which he claimed had capacity to develop structures similar to those of man. Despite the fact that his theory is currently linked with modern views; the theory never gave any plausible mechanism that would drive changes in organisms.Carolus Linnaeus is another scientist who is viewed as the father of contemporary taxonomy in relation to his work of hierarchical classification in both plants and animals. In his theory, he viewed hybridization in plants as a process that could produce new plant species. However, he still supported the theory of creation that goes against the theory of evolution. Erasmus Darwin (Charles Darwin’s grandfather) was also a very illustrious naturalist who believed that life could have originated from a common ancestor. His theory states that the disuse of organism’s parts could in their own mechanism make the parts grow or shrink.
Jean-Baptiste Lamarck’s theory of evolution is another medieval theory that has been discredited by modern experimental evidences. His theory concentrated on the idea that living organisms could transfer certain traits acquired during natural life to its offspring. He saw organisms as immutable and not permanent (Zirkle, 1941). Another theory about Evolution before Darwin’s Discovery of Natural Selection is the theory of population growth that was coined by Thomas Malthus’ between 1766-1834. According to the theory, Malthus claimed that populations could produce large number of offspring’s that could have capacity to stay alive on the available limited resources available. He viewed diseases, famine, and poverty to be the consequence of overpopulation. He never believed on the concept of evolution and he viewed the natural calamities as the wrath of God.
Charles Darwin started formulating his world-renowned theory of Natural Selection in late 1830s and early 1840s, but the process went on silent for about 25 years. Darwin conducted widespread research on animals and plants in order to learn the critical process of evolution. It was during his research work in Galápagos Islands that made him understand the theory of evolution. In his studies, he observed that birds dwelling in different islands displayed minor differences in their physical features .On one occasion he found out that different species of Finches birds had different beak sizes and shapes. After analysis, he discovered that the difference in beak sizes and shape was because of food available in particular islands (Fairfield, 2000).
Contrary to this results, Darwin results showed that their was only one specific Finches species in South America, which summed up the idea that Finches species in Galápagos could have developed from species found in central parts of South America. Further research work showed that this Finches species reproduced and survived, while those that could not familiarize themselves with environment died. As a result, Darwin concluded that organisms belonging to similar species illuminated some unique variations among them (Sober, 1984).Organisms possessing favorable characteristics showed capacity to live and reproduce, consequently passing the acquired trait genetic material to the offspring’s from one generation to another. With the help of Alfred Russel Wallace, would had also similar results for the birds he used in his studies, established similar theories which then led to development of the book On the Origin of Species, which was published in 1859 (Zirkle, 1941).
Modern Evolutionary Synthesis is defined as an amalgamation of concepts or ideas from different evolution and biological area of expertise, which gives an extensively accepted explanation of evolution. The concept of Natural Selection generally relies on the idea of heredity, which developed before the fundamental models of genetics. Evidence of natural selection in relation to “Modern Evolutionary Synthesis” Of the 20th Century relates to Mendel’s theory and research work. Despite the fact that Gregor Mendel, known to be the father of heredity who came up with principles that govern heredity, was a modern concept of Darwin work, his work became appreciated in early years of the of 20th century (Hasan, 2005). This came because of integration of Darwin theory and Mendels work which one outstanding principle is that of independent assortment which dictates that the allele pairs will separate in an independent manner during gamete formation. This is to say that the traits would be transmitted to the offspring in a manner that is independent of the other. The major explanation behind this notion relies on the Natural Selection strategy where alleles that are dominant over the others are passed over to the next generation, where the hereditary units then influence a certain trait to segregate during gamete formation.
Another evidence of natural selection in relation to “Modern Evolutionary Synthesis” Of the 20th Century relates to T. H. Morgan research work on Drosophila melanogaster. The concept of Natural Selection has helped establish a relationship between Chromosomal Theory of Inheritance and the Mendelian Theory Genetics, which has established that instead of mutations creating species in single steps, it creates variations in genetic makeup that varies among populations.
Other modern evolution advances relates to research works of W. D. Hamilton and John Maynard Smith, which have led to development of Gene-Centric View of Evolution in the mid 1960s. This synthesis has increased the extent of Darwinian Theory of Natural Selection to include consequent scientific advances that include genetics and DNA analysis. The work of G. Ledyard Stebbins, a botanist, is another most important contributor to the natural selection in relation to “Modern Evolutionary Synthesis” (Sober, 1984). His work has extended the concept of natural selection where the effects of polyploidy and hybridization shows dihybrid cross involving linkage of two genes which have no crossing over. From the Law of Independent Assortment, alleles from genes assort in an independent manner during formation of the gametes.
In recent past, some bacteria species have showed extraordinary ability to develop resistance to certain type’s antibiotics, which are commonly used to treat most common illnesses. An antibiotic refers to a natural matter or material that is released by fungi or bacteria to kill competing micro – organisms for limited available resources. In recent past scientists have discovered that some bacteria strains have started showing resistance to certain antibiotics through different mutations, or alterations in the organisms genetic material (DNA).
This resistance results in situation where changes occur in the bacteria molecular material and mostly results from events such as antibiotic over and under prescription, poor hygiene, and environmental changes. If the target bacteria obtain changes in its molecular material for genes coding a specific protein, the antibiotic then cannot bind to affected protein hence the mutant bacterial organism survive (Purdom, 2007). Under the effects of antibiotics, the process of Natural Selection occurs, thus favoring the growth, development, reproduction, and survival and of the mutant or malformed bacteria.
Concept of natural selection also plays part when bacteria obtain mutated genetic material from other micro – organisms, where they swap genetic material from each other. This allows transfer of DNA into the bacteria, thus altering its structure making them transfer new DNA to its offsprings.Presence of new DNA makes the next generation resistant to antibiotic. The concept of natural selection and mutation supports bacteria populations to become resistant to antibiotics. On the other hand, these changes through natural selection also lead to emergence of strains with defective proteins that tend to have abnormal functions.
Charles Darwin is known to be the father of evolution and heredity and came up with principles that govern heredity. His one outstanding principle is that of natural selection, which categorically states that, nature controls and selects organisms that have favorable characteristics for survival while at the same eliminating species that are inferior.
In conclusion, it is agreeable that Charles Darwin theory of natural selection is very important in respect to heredity and evolution.
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