Difference Between Allopatric And Sympatric Speciation

What Is Speciation?

Speciation is defined as the natural generative process through which new species are created from already existing species. This process is achieved by mechanisms including genetic drift and altruism and includes reproductive isolation. Genetic differentiation can be availed as the process through which a population accumulates genetic changes as a result of mutations, natural selection, and or drift. Mating barriers that may be prezygotic or postzygotic do not allow cross-breeding between two evolving populations. Together, these mechanisms come into work to accomplish the formation of new species helping in the evolution of new and various species that exist on the face of the earth.

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Allopatric Speciation

Allopatric speciation takes place in the geographical isolation of a species into distinct sub-species resulting in the formation of new species. This has the effect of keeping the isolated groups physically separated and thus does not allow gene flow from one group to the next enabling the groups to evolve in different manners.

Mechanism Of Allopatric Speciation

Geographic Isolation: Rivers, mountains or seas separate the members of a population from each other causing distinct divisions.

Divergent Evolution: The groups of population get separated and are exposed to various environmental conditions and gene changes, which in due course, give rise to genetically diverse populations adapting to their surroundings. This leads to the formation of new species these populations build up a set of genetic variations as time goes on.

Examples Of Allopatric Speciation

Darwin's Finches: All those finch species which are seen at present evolved from the same ancestor; however, the situation on every island is different.

Grand Canyon Squirrels: You will find two types of squirrels, the Kaibab squirrel which belongs to the north of the Grand Canyon and the Abert’s squirrel which belongs to the south of the Grand Canyon and are two different species of squirrels.

Sympatric Speciation

This is the type of speciation in which the evolution of a new species from an original ancestor species occurs physically in the same region. It is the type of speciation that happens when no geographical isolation of the population is involved.

Mechanism Of Sympatric Speciation

Reproductive Isolation within the Same Geographic Area: Species in a population adapt to new conditions and develop characteristics which make them unsuitable for mating with other populations even when they are in the same geographical region.

Polyploidy, Sexual Selection, Habitat Differentiation: Mutation, such as changes in chromosome number polyploidy, may lead to reproductive isolation. Mate choice is based on sexual selection whereas choice of habitat results in differentiation of population concerning the ecological factors that cause speed of speciation.

Examples Of Sympatric Speciation

Apple Maggot Flies: These flies have diverged into various subgroups depending on the type of fruit they are attracted to, while some go for apples, others for hawthorn.

Cichlid Fish in African Lakes: It is noteworthy that although all the studied fish live in the same waters – the lakes of East Africa, different cichlid species have developed different ecological and/or mating niches.

Comparison Between Allopatric And Sympatric Speciation

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