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Speciation

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Introduction

MVSAT 2024

Speciation refers to the process of how a new kind of animal or plant species is formed. It is an evolutionary process that leads to the formation of a new and distinct species that is reproductively isolated from another species. 


Speciation is also called ‘cladogenesis’, which means arising from a splitting event where the parent is split into two distinct species.


Types of Speciation

There are 5 types of speciation which include-

Allopatric Speciation- When a species is separated into two groups that are separate and isolated from one another, the type of speciation is known as allopatric speciation. This type of speciation occurs if any geographical changes occur. The geographical changes may include the formation of mountains by volcanoes, the formation of an island, human activities leading to habitat fragmentation, glaciers and rivers causing habitat separation and so on. 


An example of Allopatric Speciation is Darwin finches which led to the theory of evolution.

Peripatric Speciation- Peripatric Speciation occurs when a small group of individuals separate from a larger group and form new species. It is the mode of species formation in which speciation occurs from an isolated peripheral population. In this type of speciation genetic drift plays an important role.


Parapatric Speciation- When a part of an environment has been polluted, the type of speciation that occurs is known as parapatric speciation. Polluted environments include mining activities that leave waste with high amounts of metal such as lead and zinc.


Sympatric Speciation- The type of speciation when there are no physical barriers to prevent any members of a species from mating with one another. All members are in close proximity to one another in this type of speciation. This type of speciation is common in herbivore insects when a new plant is introduced into a geographical range of species.


Artificial Speciation- The creation of new species by people is known as artificial speciation. An example of artificial speciation can be seen in fruit flies (Drosophilia Melanogaster). Artificial speciation is also known as artificial selection.


Factors Affecting Speciation

The factors that lead to speciation are as follows-

  • Genetic Drift- The process describing random fluctuations in the frequencies of allele frequencies in populations is known as genetic drift. Genetic drift eventually leads to the formation of new species by causing a population of organisms to be genetically distinct from the original population.

  • Natural Selection- The selection by which organisms are more likely to survive and reproduce is known as natural selection. Natural selection eventually leads to speciation.

  • Geographic isolation- The mechanism of speciation in which populations of species are divided by geographic barriers. These geographic barriers may include rivers, water bodies and mountains.

  • Mutation- Over a long period of time, the accumulation of many small genetic changes in a population occur, these changes are known as mutations. 

Reproductive Isolation- The inability of a species to breed with related species due to barriers or differences such as genetic, geographical, physiological, and behavioral.

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FAQs on Speciation

1. What is Speciation?

In simple words, Speciation is a process of forming a new kind of species from the existing ones. There are several reasons for this process. 

2. How Does Speciation Take Place? 

Speciation takes place in 3 stages- separation, adaptation and reproductive isolation. 

3. How Fast Speciation Happens?

Process of Speciation takes a long period of time. It usually occurs after thousands of years or many decades. 

4. What is the most common example of speciation?

The most common example of speciation is Galapagos Finches. In different islands of the Galapagos Archipelago, which are located in the Pacific Ocean, different species of finches make their homes that are isolated from one another because of the oceans. Based on the availability of different types of food sources, the beaks of the finches have adapted different shapes. Since the birds are isolated and have their unique characteristics, they can not breed with one another.

5. Which is the most common type of speciation?

The most common type of speciation is allopatric speciation. When the populations of the two same species isolate from each other because of geographical changes, allopatric speciation occurs. The geographical changes that might occur include the formation of new mountains, oceans and other water bodies. An example of a geographical barrier is the Isthmus of Panama which is separated by the Atlantic and the Pacific Ocean. Allopatric speciation is further divided into two models- peripatric and vicariance.

For more details on Allopatric Speciation, Vedantu has provided study material which the students can refer to study the topic in depth.

6. Who coined the term 'speciation'?

Orator F. Cook coined the term Speciation in 1906 for cladogenesis which means splitting of lineages. The opposite term for cladogenesis is anagenesis which means phyletic evolution within the lineage. Speciation leads to the following things-

  • Splitting of phylogenetic lineage

  • Formation of new species

  • Discontinuities between populations

  • Splitting of a species into two or more species


Kaibab and Abert’s squirrels are examples of speciation which are separate species of squirrels that evolved after the formation of the Grand Canyon.

7. What is hybridization in Speciation?

Hybridization is the artificial process by which humans form new species which inevitably occurs during Speciation. When two divergent lineages having independent evolutionary histories mate, hybrid speciation occurs. Hybridization has an impact on the speciation process. It can slow down the process, accelerate the process and have many other multiple effects at various stages. When the hybrid populations isolate from the parent lineage, which leads to divergence from parent populations, hybridization can result in speciation.

8. What is selection in Biology and which selection is used in speciation?

The preferential survival and reproduction of individuals with certain genotypes either by natural or artificial controlling factors is known as selection.

The selection used in Speciation is natural selection, proposed by Charles Darwin in 1958. In the absence of competition, for food, spaces or mates, between organisms, the selection is based completely on environmental factors which include seasonal variations. This type of selection is known as natural selection.


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