Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

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  Allopatric speciation

• Allopatric speciation

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  Allopatric speciation

• Allopatric speciation

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  Allopatric speciation

Allopatric Speciation

Allopatric speciation is a mode of speciation that occurs when biological populations of the same species become isolated from each other to an extent that prevents or interferes with gene flow. The term "allopatric" is derived from the Greek words "allos," meaning "other," and "patris," meaning "fatherland." This form of speciation is considered one of the most common mechanisms by which new species arise.

Mechanism

Allopatric speciation typically involves the following stages:

Geographic Isolation

The initial step in allopatric speciation is the physical separation of populations. This can occur due to various geographic barriers such as mountain ranges, rivers, oceans, or deserts. These barriers prevent individuals from different populations from interbreeding.

Genetic Divergence

Once isolated, the separated populations undergo genetic drift, mutation, and natural selection independently. Over time, these processes lead to genetic divergence. The differences in allele frequencies between the populations increase, leading to distinct genetic identities.

Reproductive Isolation

As genetic divergence continues, reproductive isolation mechanisms develop. These mechanisms can be prezygotic, such as differences in mating rituals or timing, or postzygotic, such as reduced viability or fertility of hybrid offspring. Once reproductive isolation is established, the populations are considered separate species.

Examples

One classic example of allopatric speciation is the Darwin's finches on the Galápagos Islands. These birds are thought to have originated from a common ancestor but have diversified into multiple species due to geographic isolation on different islands.

Another example is the squirrel populations on either side of the Grand Canyon. The Kaibab squirrel and the Abert's squirrel are separated by the canyon and have evolved into distinct species.

Importance in Evolution

Allopatric speciation is a fundamental concept in evolutionary biology as it explains how new species can arise from a common ancestor. It highlights the role of geographic and environmental factors in shaping the biodiversity of our planet.

Related Pages

• Sympatric speciation
• Peripatric speciation
• Parapatric speciation
• Reproductive isolation
• Evolution