Charles Darwin's Theory Of Natural Selection

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Evolution is the change of phenotypic or genotypic traits in individuals that has been successfully passed onto future generations.4 The biologist, Charles Darwin’s theory of evolution associated with natural selection is influenced by the conditions in which individuals live in. 1 As natural selection favors individuals with more variation, these individuals are more likely to survive and reproduce 3 and those individuals then pass down those favorable genes onto the next generation.2 Over time, these favorable genes accumulate and characteristics from the later generations then diverges from the initial and ancestral state.3 Even in a species, variation can occur due to environmental factors such as mutation, genetic drift or selection.3…show more content…
When an individual is infected, mechanisms in the body will avoid the infection and once individuals are recovered from it, it reduces the chances of pathogenicity.2 By using selection as an intervention means that the resistant alleles can be anticipated to exist among populations and communities. These alleles prompt evolution in both innate and adaptive immunity with the defense. When selection occurs, the variation in allele frequency can be drastically different from the initial frequencies.6 For example, individuals who are heterozygous for sickle-cell anemia are at an advantage as they are resistant to Malaria.4 This mutation was initially observed between 3000 to 11000 years ago when there was a high frequency of Malaria occurrence.4 The mutation for sickle-cell anemia occurs in high frequency at locus where individuals with Malaria have occurrence at, thus maybe the reason for individuals to be resistant to Malaria.4 It is concluded that individuals that…show more content…
Over time, evolution can act on physical traits as well as genotypic characteristics, with migration acting as pressure and our environment changing regularly.6 An example would be the evolution of humans having bigger brains compared to ancestors.6 Studies have found that humans have at least three duplications of a gene called SRGAP2 while non-humans contain one and it is speculated to be the reason why humans have bigger and better adapted brains.6 Even though there are not much differences in the genome between chimpanzees and humans, there is a considerable amount of difference in brain capacity with humans having more potential.6 The existence of neurons and neurotransmitters give humans the ability to transmit signals which is employed in the development of the brain.6 The increase in the size of humans brains are also partly due to the adjustment of cognitive functions that assist to survive under different environment circumstances.3 As evolution of the brain continues, the changes observed to brain tissues are due to pressures like natural selection or mutation of genes.3 For instance, environment factors that may influence phenotypes are climate, food supply and predators while culture may alter the gene within an individual.4 By using climate change as an example and looking at Charles Darwin’s theory of evolution, individuals that are suitable and fitted for that environment will survive and is more likely to reproduce which then passes on the favorable trait to
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