The Mechanisms of Biological Evolution

Biological evolution occurs with a particular mechanism. Some of the mechanisms that lead to the occurrence of evolutionary biology of these are events of changes in the nature or mutation, selection, and changes in gene frequency.
Biological evolution occurs due to genetic variation and natural selection. Darwin said that the offspring of the marriage will vary. Offspring according to the environment will survive, while the offspring who did not adapt will become extinct. The variation in the offspring may occur through genetic mutation and recombination of genes in a single offspring.

• Gene Mutation.

Mutation is one of the causes of variation. In living cells, DNA is a chemical structure that constantly changes, especially when it is undergoing replication events. Generally,changes in the structure can be repaired immediately. However, there are some changes that can not be repaired or there is a failure in DNA repair. This causes a mutation known as gene mutations. Gene mutation is a change in the structure of genes (DNA) that can cause changes in the nature of an organism and is declining. By changing the structure of DNA there will be a different gene expression giving rise to new traits in organisms.
The change will cause the formation of the nature of variation within an organism. The existence of mutation events can alter the composition of alleles in a population. For example, a mutation of  A gene will be  a gene will increase the frequency of  a alleles in the population. Conversely, mutation of a gene into A gene will increase the frequency of A in the population.

• Selection.

Events in the natural selection of living beings due to the influence of industrialization and the use of insecticides. For example, because the effect of air pollution due to industrialization, the bark where it perched by butterflies that had been colored from white to black. This causes the butterflies that had changed color to from white to black too, adjusted the color of the bark where the animals landed. Discoloration of the butterfly is one attempt to protect themselves from predators.

• Changes in Genotypic Frequencies within Populations.

Total collection of genes in a population at a particular period is referred to as a collection of genes (genetic pool). This gene collection consists of all pairs of genes or alleles at all loci of genes that were present in all individuals making up the population.gene frequency is the comparison between genes or genotyping the one with the other genotypes in a population. For example, in a region there is a population of plants with red flowers symbolized genotypes AA and plants with white flowers for aa that are equally adaptive. If carried out a cross you will get such plants as follows:

P             : 50% AA                                   ><                         50%
F1           :                                               100%
Gametes : A = 50%                                                           a = 50%

Genotype	50% A	50% a
50% A	25% AA	25% Aa
50% a	25% Aa	25% aa

So the frequency of genes in F2 = 25% AA    : 2 (25%) Aa   :  25% aa
                                                    = 25% AA    : 50% Aa         : 25% aa
                                                    = 1/4 AA      : 1/2 Aa           : 1/4 aa

Based on the results of the calculation above, the genotype frequencies will be balanced when F2 equal to the product of the frequency of genes from each parent, or can be expressed with the symbol (A + a) x (ax A) = A + 2Aa + a or AA + 2Aa + aa.

• Several Factors That Cause Changes in The Population Genotype Frequencies.
1. Mutation.
2. Natural selection.
3. Migration.
4. Genetic recombination and selection.
5. Genetic drift.

• Adaptation, Speciation, and Extinction.

Adaptation is the ability of an individual to adjust to the environment. Adaptation is a genetically controlled trait that helps an organ or an individual to be able to live and breed in accordance with the environmental habitat.
Biodiversity on this earth, is the result of two main processes of speciation and extinction. The species is a group of interconnected mating (interbreeding group) and different from each mating group to another. An organism is said as a species if they are able to mate and produce fertile offspring. Groups within a species have much in common, whether genetic, morphology, physiology, and behavior.
The process of forming new species and different from the previous species in evolutionary terms is called speciation. The process of forming new species can be caused by several things, there are hybridization, domestication, and reproductive isolation.


Until here the material for today from me. For some reason, my inspiration ends here.Maybe I'll connect it to another time. Thanks for reading. May be useful for a loyal visitors of Sky of Shiroi Kiba.