Natural Selection Hypothesis

In population genetics aspects, we can infer that we agreed that evolution happened. Darwin 's Theory of Evolution by Natural Selection is also one of the best explanation for the existence of evolution. Why do we agree that evolution exist based on prove in population genetics? The involvement of genotype factors show how an organism evolved over time. This can be relate to Darwin’s theory too in which in natural populations, the genetic composition of a population 's gene pool may change over time. Before Darwin 's time, science knew that life evolved, since they saw the fossil and their resemblance to extant life. And many hypotheses had been proposed before Charles Darwin 's idea. Darwin identifying natural selection as the mechanism for

Unfortunately, he did not have a good explanation for how new traits were formed, as there was very little knowledge of genetics at the time. We now know that genetic mutations provide the possible traits for natural selection to act upon. So, mutations provide the traits and natural selection weeds out the traits that do not work, leaving the best to carry on.

Other than that, with evolution can happen due to mutation which happened and it change the genotypic and phenotypic of an organism overtime. Mutation is the primary source of new alleles in a gene pool, but the other factors act to increase or decrease the occurrence of alleles. Mutations are classified as beneficial, harmful or neutral. Harmful mutations will be lost if they reduce the fitness of the individual. If fitness is improved by a mutation, then frequencies of that allele will increase from generation to generation. The mutation could be a change in one allele to resemble one currently in the population,

Mutations are generally deleterious and are selected against. But the genome of a species can undergo another type of change, gene duplication, which actually favors mutational events. If a single gene that is important undergoes a duplication, mutation in the duplicated copy would not necessarily reduce the fitness of the individual because it still would have a functioning copy of the original gene. With this adaptive constraint removed, further changes can occur that generate a new gene that has a similar function in the organism, but may function at a specific time in development, or in a unique location in the individual. This type of evolution generates multigene families. Many important genes such as haemoglobin and muscle genes in humans and seed storage and photosynthetic genes in plants are organized as multigene families.

The process of evolution is slow and continuous. We have seen that many generation of persistent selection are required to drastically reduce the frequency of an unfavourable mutant gene in the population. Likewise, it generally takes an inordinately long period of time for a new favourable mutant genes to replace its alleles throughout a large population. We have encountered situations in nature which a favourable mutation has spread throughout a population in a comparatively short span of