Answer:
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: