Allopatric And Sympatric Speciation: Definition, Differences and Examples

A species is a group of organisms that can reproduce new fertile individuals and thus produce even more offspring. As a result, two organisms that cannot reproduce and produce fertile offspring belong to different species. The origin of new species is referred to as speciation. The two major mechanisms for the formation of new species are allopatric speciation and sympatric speciation. The term allopatric is derived from the Greek words allos, which means "other," and patris, which means "fatherland." Allopatric speciation occurs when an organism's population becomes separated or isolated from its main group. The word sympatric is derived from the English prefix sym-, which means "same" or "together," and the Greek word patris, which means "fatherland." This type of speciation occurs in populations that are not geographically isolated. Let’s discuss more on allopatric and sympatric speciation.

Key takeaways: Speciation, Factors affecting speciation, Allopatric Speciation, Sympatric Speciation, Autopolyploidy, Allopolyploidy

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What is Speciation?

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A species is a group of organisms that have similar characteristics and can interbreed to produce offspring. Speciation, on the other hand, is the process of creating new species from existing ones as they evolve as a result of external factors such as geography. The formed species are reproductively isolated from their previous species, which means they cannot interbreed.

Factors Influencing the Speciation Process

There are numerous factors that contribute to speciation in the environment, including:

Geographical isolation: occurs when a number of species migrate to different areas and are unable to interbreed due to a variety of factors such as mountain rise, continental drift, organism mate, and so on, resulting in speciation.

Reduced Gene Flow: When two individuals are unable to mate due to a variety of factors, there is a possibility of reduced gene flow but not total isolation.

Hybridization: Hybridization is a man-made method of creating new species. In animal husbandry, two parents of different species mate to create a third species. Hybridization has a wide range of effects on the speciation process.

The Benefits of Speciation

• There are several benefits to speciation, and they are as follows:
• Speciation teaches organisms how to survive in harsh environments.
• It improves the ecological balance of abiotic and biotic elements.

Disadvantages of Speciation

• Cannot be used to obtain fossil records.
• Asexual species do not have it.
• Only applied to geographically isolated populations.

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Allopatric Speciation

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Allopatric speciation occurs when an organism's population becomes separated or isolated from its main group. Natural selection causes changes in the allele frequency in the new group, which was previously homogeneous across individuals, over time as a result of pressure from differences in predators, climate, competitors, and resources. For a variety of reasons, populations can become isolated. Changes in land topography caused by earthquakes, seeds dispersed by the wind and carried away in rivers, flooding, migration, and erosion are a few examples. Darwin's Finches and squirrel populations in the Grand Canyon are two examples of allopatric speciation. According to research, the greater the distance between species, the greater the likelihood of speciation.

Examples of Allopatric Speciation

Darwin's Finches

It is a major example of allopatric speciation in Galapagos finches that Charles Darwin observed. There are 15 different types of finches on the Galapagos Islands, each with unique characteristics such as a beak for eating different types of food, but all finches have common ancestors that evolved due to isolation on different islands. The birds that survive become common in their environment and form a variety of species. This is referred to as adaptive evolution.

Squirrels of the Grand Canyon

When they form, they form a natural barrier between the squirrels that live in the area. Squirrel populations became separated due to geographical changes, and they were distributed in different areas, resulting in two distinct species.

Also Read: Silkworm Life Cycle

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Sympatric Speciation

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Sympatric speciation occurs in populations that are not geographically isolated. Changes in the organism's chromosomes are the primary mechanisms resulting in sympatric speciation. This can occur when a serious error occurs during cell division, resulting in more than one copy of a chromosome(s) or the loss of a chromosome(s) in one of the daughter cells. This is a condition known as aneuploidy, and there are two types:

Autopolyploidy

An organism in this situation has two or more sets of chromosomes from its own species. This is what happens in plants when all of the chromosomes move to one of the daughter cells during meiosis. When this occurs, the resulting gametes are incompatible for reproduction with those of either parent. The organism, on the other hand, can self-pollinate or reproduce with another organism with the same number of chromosome pairs.

Allopolyploidy

When two different species mate and produce offspring, the allopolyploidy form of sympatric speciation occurs. To form viable offspring, the first-generation offspring's gametes must combine with normal gametes from one of the two original species. A polyploid species can be traced back to the origins of nearly half of all plant species. Cultivated tobacco, cotton, and wheat are examples of these.

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Difference Between Allopatric and Sympatric Speciation

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Things to Remember

• Allopatric speciation refers to the physical isolation of a population due to an extrinsic barrier. Allotropic speciation refers to the physical isolation of a population due to an extrinsic barrier.
• Sympatric speciation refers to the evolution of new species from one ancestral species that live in the same habitat.
• There are two types of sympatric speciation: Autopolyploidy: An organism in this situation has two or more sets of chromosomes from their own species and Allopolyploidy: When two different species mate and produce offspring, the allopolyploidy form of sympatric speciation occurs.
• Allopatric is a type of physical barrier. In sympatric speciation, the 4n chromosome replaces the 2n chromosome. Diploids and tetraploids cannot mate in sympatric speciation.

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