Difference Between Allopatric And Sympatric Speciation

Edited By Irshad Anwar | Updated on Nov 27, 2024 08:01 PM IST

The two major speciation modes are allopatric speciation and sympatric speciation, explaining how new species come into being. Allopatric speciation is the process by which populations of the same species become geographically isolated from one another, which blocks gene flow and allows new species to emerge. In contrast, sympatric speciation occurs without geographic separation. It is often caused by factors like ecological niche differentiation or genetic mutations within a shared environment. This is an important topic from the Evolution Chapter of Biology.

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What is Speciation?
Allopatric Speciation
Sympatric Speciation
Comparison Between Allopatric and Sympatric Speciation

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.

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

Feature	Allopatric Speciation	Sympatric Speciation
Geographic Isolation	Yes, populations are physically separated	No, populations are in the same geographic area
Mechanisms	Geographic barriers leading to divergence	Reproductive isolation, polyploidy, Natural selection, habitat differentiation
Examples	Darwin's finches, Grand Canyon squirrels	Apple maggot flies, cichlid fish in African lakes
Reproductive Isolation	Arises as a result of geographic separation	Occurs within a shared environment
Genetic Divergence	Driven by isolation and different selection pressures	Driven by niche differentiation and mating preferences

Also Read

Mutation Theory	Reproductive Isolation
Evidence of Evolution	Miller Urey Experiment
Mutagens	Anagenesis

Frequently Asked Questions (FAQs)

1. What is the main difference between allopatric and sympatric speciation?

The main distinction from the previous type is that it happens due to physical barriers that isolate populations and cause the development of distinct species in different environments. On the other hand, sympatric speciation occurs in one area without the separation whereby speciation might as a result of reproductive isolation, polyploidy, or ecological niches.

2. Can sympatric speciation occur in animals?

Yes, sympathy is possible for animals and thus sympatric speciation is possible. For example, cichlid fish in the African lakes demonstrate sympatric speciation wherein different species develop from the same breeding population within the same lake through differences in mating behaviour and preferences and/or the usage of benthic or limnetic zones.

3. How does geographic isolation lead to allopatric speciation?

Allopatric speciation happens through physical barriers such as mountain barriers or a river which separates a population. This leads to the inability of the isolated populations to interbreed – thus, they will undergo different paths of evolution through the mechanisms of natural selection and genetic drifts, which culminate in the formation of new species.

4. What are some examples of sympatric speciation?

Sympatric speciation can be illustrated with examples of apple maggot flies which evolve into different species depending on the type of fruits chosen and cichlid fishes of the African lakes.

5. Why is understanding speciation important in evolutionary biology?

The study of speciation is central in evolutionary biology as this field describes the process of formation, adjustment, and variety of new species. It can explain the underlying mechanisms of species to richness and assist in preservation because it demonstrates how species adapt to alterations in the environment and human interference.