What are the three major mechanisms of evolution differ in how they work

Evolution is the process through which the different organisms advances from having less developed form or the position into a less-perfect form. As, different species go through different pathways in which they attain a new and complex form of mechanism to survive inside a region or given parameters.While, the process of evolution takes place in a three main different forms or ways, or briefly in three different pathways:The natural selection: Species goes through different process in which they deal with the number of obstacles, like the limitation of food resources, having the competition for the shelter and resources etc. During, such a process the species either goes into extinction or they survive for a much longer time then expected.The Genetic flow: The species have a given set of genes or more over genome which they posses for having a specific identity among the diverse form of organisms.The different species may go through the mutations or even may go through the different form of gene losses. As, due to the changes inside the overall environment or the system of the organisms the difference or diversity inside the genome of the organisms may occur.  The Genetic drift:  The genetic drift is the displacement which causes the changes inside the different species over all existence. For example, lets genetic drift may be termed as the process which is brought by a set of species which are detached from its over all population and it brings change along with variety by introduction of that small population inside the given region.                                                                                                                                                                                                                      

Mechanisms of Evolution.

Generally an individual do not evolved, the population of individuals in the population actually evolved.The collection of the gene in a population is  called gene pools, and it is the factor  within the  population  that is responsible for evolution  of population. This gene pool  can be altered within the population by mutation, which produces variation in the organism.Thus  mutations is  the driving force for changes in  the gene pool of  population .

When population of organisms  migrates from one  region to another. Assuming they mate with  new organisms  of the same species, their gene pool is  exchanged  at fertilization. Thus  they contributed  new gene to  population,This genetic  contribution from migration of gene pools i s called Gene flow.

Assuming   small population of individual migrated to  new area far away from the original location, and are thus  geographically isolated, As they interbreed new group of individual evolved, different from their original population, due to variation  by mutation. This process is called Gene Drifts.it usually take place in small population, and it depends on random sampling of alleles of individuals in the population.

As individual in the population are exposed to selection pressures, mostly competition for ,mating partners, foods, space, effects of diseases, the population of individual are affected.However some organisms in the population may be able to resist  these selection pressure, and therefore survive, while those without these characteristic fizzled out of the population. The surviving  organisms  were  the fittest. They must have possessed certain characteristics or gene, which makes them to resist the selection  pressure, and therefore survive ahead of  the weak ones. Thus they have been naturally selected by nature.

if these continues over many generation, they will pass this traits/gene to their  offspring,and with time their population dominated the population. Thus they have emerged or evolved to new species of organism. This is evolution by natural selection by survival of the fittest.

Explanation:

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