Explain the origin of species?

The origin of species is also known as speciation. The new species develop from the already existing species. There are a lot of factors which play an important role in the development of new species. The genetic drift removes the certain genes of a particular character. It happens when there is a natural calamity. In this gene frequency of the population changes and this may happen due to loss of gene or the proper distribution of gene. For example, a dwarf couple when isolated will always produce the dwarf off springs. The structural and functional changes do occur with the variations and adaptations to form new species. There occurs a physical barrier between the species which form a group of populations which are isolated. It involves the fissure formation, formation of large body, valley flooding etc. This prevents the interbreeding. The isolated group develops certain variations which form different races. They have different color and behavior. They have different morphology too. However, when these races are brought together the inter breeding do not happen than also. This occurs due to drifting. There is a reproductive barrier in which the opposite ends of a range prevents the individuals of same population to breed in between. If there is a reproductive isolation it leads to the evolution of other groups in the different directions. During the initial stages these groups interbreed but later on they do not interbreed. They interbreed when they are in contact. They do not interbreed when they are not in contact and they move from each other. This barrier may occur due to the differences in mating period, mating seasons, morphological differences, anatomical and physiological differences. The mutations occur suddenly but are stable. They are hereditary and are non continuos variations. These give rise to new species suddenly. It includes the ancon sheep and hornless cattle. A few of cells undergo polyploidy. It increases the number of chromosomes. It is very common in plants. It prevents breeding with the normal individuals.
There are different types of speciation. It includes the allopatric and sympatric speciation. The allopatric means which occur in the other native land and one part of population occurs in the other area. This area is not common. The population gets separated and forms a new species. The sympatric means which occur in the same native land and the different parts of population occurs in the same area. This area is common. The population gets separated and forms a new species. So a reproductive isolation plays a vital role in this type of speciation.