Allopatric and Sympatric Speciation

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What is Speciation

A species is a group of organisms showing similar features and can interbreed among themself to produce their offspring.Whereas speciation is a process of formation of new species from existing species as they evolve due to certain factors like geographical factors. They formed species are reproductively isolated from their previous species i.e, they cannot interbreed among themselves.


Factors Affecting Speciation Process

There are many factors which lead to speciation in environment, they are:

  1. Geographical Isolation: When a certain number of species move to different areas and due to this factor they cannot interbreed among themself due to several obstacles like mountains rise, continental drift, organism mate,etc  and this leads to speciation.

  2. Reduction of Gene Flow: in case when two individuals are not able to mate because of several factors then there is chances of reduced gene flow but not total isolation.

  3. Hybridisation: Hybridization is an artificial method of developing a new species. In animal husbandry, two parents from different species are mated to form a third species. Hybridization has numerous and various impacts on the process of speciation.


Advantages of Speciation

There are several advantages of speciation they are:

  1. Speciation teaches organisms to live under adverse conditions.

  2. It enriches the ecological balance of abiotic and biotic components.


Disadvantages of Speciation

  1. Cannot be taken for fossil records.

  2. Absent in asexual species.

  3. Only applied to populations that are geographically isolated.


Allopatric Speciation

This type of speciation happens when two populations of the same species become isolated from each other due to geographic factor. As speciation is a slow process due to which populations evolve into different species. A species is defined as a population which can interbreed among themself, so during the speciation process population form two or more distinct species that can no longer interbreed among themself.


Example of Allopatric Speciation:

  1. Darwin's Finches

It is a major example of allopatric speciation that occurs in Galapagos finches that charles darwin. All total there are 15 types of finches on the Galapagos islands and all of them have specific features like beak for eating different types of food, but all finches have common ancestors, because of isolation to different islands they evolved. The birds who survive successfully become prevalent in their environment and they form a variety of species. This evolution is known as adaptive evolution.


  1. Grand Canyon Squirrels

When they are formed they create a natural barrier between the squirrels living in the area. Squirrels populations were separated due to geographical changes and they got distributed in different areas and became two different species.


Sympatric Speciation

Speciation occurs when two groups of the same species who live in the same geographical location, but they evolve differently till they can no longer interbreed and they are considered as different species. This type of speciation is seen in different types of organisms like bacteria,fish, apple maggot fly. But it is difficult to find when sympatric evolution occurred or occurring in nature. It elove the population of new species when they are divided by geographical barriers. This evolution happens without any geographical isolation , under this evolution change in chromosomes occurs.


There Are Two Ways of This Type of Speciation They Are

  1. If error occurs during cell division known as autopolyploidy.

  2. If there is more than one copy of chromosome or loss of a chromosome in one of the daughters and they are known as allopolyploidy.

  1. Autopolyploidy: As an organism has two sets of chromosomes but due to certain abnormality if the daughter cell has more than two sets of chromosomes then this condition is known as autopolyploidy.

  2. Allopolyploidy: this type of speciation occurs when two different species mate and form new offspring. Example: tobacco, cotton, etc.

Difference Between Allopatric and Sympatric Speciation

Allopatric Speciation

Sympatric Speciation

1. Geographical isolation is needed.

1. Geographical isolation is not needed.

2. Natural selection is a major differentiation method.

2. Polyploidy is a major selection method.

3.Creation of new species processes is fast here.

3. Under autopolyploidy the process is fast and under allopolyploidy this method is slow.

4.It is commonly seen in both plants and animals.

4. It is commonly seen in plants.

5.Example: Darwin finches, Grand canyons.

5. Example: wheat, tobacco, etc.


Facts on Allopatric and Sympatric Speciation

1.Allopatric is a speciation from a physical barrier.

2. In sympatric speciation the 4n chromosome is formed instead of 2n.

3. In sympatric speciation diploids cannot mate with tetraploid.


MCQ On Allopatric and Sympatric Speciation:

1. Which of the Following Does Not  Tend to Promote Speciation?

A)  Founder Effect                

B)  Reproductive Isolation

C)  Natural Selection

D) Gene Flow

Answer: (D)


2. Which of the Following Statements Explains Why Animals Are Less Likely Than Plants to Speciate by Polyploidy?

A) Animals have behavioral rituals that result in mate recognition.

B) Animal movement patterns insure gene flow.

C) Animals rarely self-fertilize, so diploid gametes are much less likely to fuse.

D) Animal chromosomes are less likely to replicate incorrectly than plants.

Answer: (C)


3. The Two Key Factors Responsible for Speciation Among Populations Are

A) Mutation and heterozygote disadvantage

B) Reproductive isolation and genetic divergence

C) Postzygotic isolation and morphological change

D) Mutation and genetic drift 

Answer: (B)


4. In Which Theory of Speciation Does a New Species Emerge from Within the Geographic Range of Its Ancestor?

A) Allopatric speciation

B) Parapatric speciation

C) Sympatric speciation

Answer: (A)

FAQ (Frequently Asked Questions)

1. What is Speciation?

It is a process under which  groups of organisms showing similar features can interbreed among themself to produce their offspring.Whereas speciation is a process of formation of new species from existing species as they evolve due to certain factors like geographical factors.

2. What is Allopatric Speciation?

This type of speciation happens when two populations of the same species become isolated from each other due to geographic factor. As speciation is a slow process due to which populations evolve into different species.

3. What is Sympatric Speciation?

This type of speciation occurs when two groups of the same species who live in the same geographical location, but they evolve differently till they can no longer interbreed and they are considered as different species.

4. Factors Affecting Speciation?

There are several factors affecting speciation are:

  1. Geographical Isolation: Isolation which occurs due to several geographical factors like mountain ranges, rivers, etc due this organism of the same species cannot interbreed among themself.

  2. Reduction in Gene fFow: Due to isolation, reduction in gene flow occurs.

  3. Hybridisation: it is an artificial mode of speciation.