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Tuesday, 16 January 2018

Speciation: Definition and Types

  By GK Planet Team       Tuesday, 16 January 2018

 Speciation: 4 Types of Speciation


Speciation definition and its four type are as follows:
  Speciation is about how species form. It is a major part of evolutionary biology.
  Speciation events are believed to happen under a number of conditions. Scientists generally believe it takes place because members of the same species have become isolated from one another.
Speciation is the formation of one or more new species from an existing species.
  Speciation most often occurs due to geographic isolation or reproductive isolation of individuals within the population.
  Reproductive isolation means that for whatever reason, one or more organisms are prevented from being able to reproduce with others in the population of that species.
  With reproductive isolation organism itself changes because of random mutation(s) and also environment changes, causing separation of the population into two or more subgroups of the original population.

Types of Speciation

  There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric.
  Speciation may also be induced artificially, through animal husbandry, agriculture, or laboratory experiments.

Four Types of Speciation in Detail

  1. Allopatric
  2. Peripatric
  3. Parapatric
  4. Sympatric

Allopatric Speciation

  Allopatric speciation occurs when members of a population are separated by a geographic barrier and become two separate species.
 
During allopatric (from the ancient Greek allos, "other" + Greek patrā, "fatherland") speciation, a population splits into two geographically isolated populations (for example, by habitat fragmentation due to geographical change such as mountain formation).
  In the case of allopatric speciation, an actual geographic boundary physically separates the species. A river or a mountain range, for example, may cause a species to diverge.

Peripatric Speciation

  Peripatric speciation occurs when a small group becomes isolated from the main body of the species. Since this cluster is just a small portion of the whole population of the species, all of the genetic differences which make the species robust may not be present. This presents what evolutionary biologists call a bottleneck. Some of the genes that flow within a species have been clipped off and separated from the gene pool.
Peripatric speciation happens, when small groups of individuals break off from the larger group, become geographically isolated, and form a new species. Genetic drift may happen here.

Parapatric Speciation

  Parapatric speciation occurs when a species is spread out over a large, continuous geographic area, but individuals tend to mate successfully only with members from their own region because the species are separated by extreme differences in the same environment.
  With parapatric speciation, a species is spread out across large areas with diverse environments.
  Species adapt to these new areas and gradually become separate species.
  There's no defining geographical feature that separates these animals
  They may become separate species simply because of the distance that separates the groups.

Sympatric Speciation

  Speciation in which new species evolve from a single ancestral species while inhabiting the same geographic region.
In the case of sympatric speciation, members of a species continue to live side by side, but still separate into different species. For example, some insects feed and reproduce on a single type of fruit. If some members of this species try another type of fruit, their offspring may be raised to visit that fruit as well. If this happens, the members of a species may diverge into two species based solely on the fruit they feed on and lay eggs in.

Factors Influencing Speciation:

Following factors influence the speciation:

1. Mutation: Mutation, an alteration in the genetic material (the genome) of a cell of a living organism or of a virus that is more or less permanent and that can be transmitted to the cell's or the virus's descendants.
2. Recombination: Genetic recombination is the production of offspring with combinations of traits that differ from those found in either parent. In eukaryotes, genetic recombination during meiosis can lead to a novel set of genetic information that can be passed on from the parents to the offspring.
3. Natural selection: Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.
4. Hybridization: Genetic hybridization is the process of interbreeding individuals from genetically distinct populations to produce a hybrid. A genetic hybrid would therefore carry two different alleles of the same gene.
5. Genetic drift: Genetic drift describes random fluctuations in the numbers of gene variants in a population. Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time. These variations in the presence of alleles are measured as changes in allele frequencies.
6. Polyploidy (to be described): Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (Eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.
7. Isolation: A genetic isolate is population of organisms that has little genetic mixing with other organisms within the same species. This may result in speciation, but this is not necessarily the case.

Frequently asked on Speciation and its types


How do we get speciation?

Sympatric speciation occurs when populations of a species that share the same habitat become reproductively isolated from each other. This speciation phenomenon most commonly occurs through polyploidy, in which an offspring or group of offspring will be produced with twice the normal number of chromosomes.

What are the different types of speciation?

This is called allopatric speciation. There are four types of speciation: allopatric, peripatric, parapatric, and sympatric.

What are the four modes of speciation?

There are four geographic modes of speciation in nature, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric.

What is the Peripatric speciation?

Peripatric speciation is a mode of speciation in which a new species is formed from an isolated peripheral population. Since peripatric speciation resembles allopatric speciation, in that populations are isolated and prevented from exchanging genes, it can often be difficult to distinguish between them.

What is the difference between allopatric and sympatric speciation?

Allopatric speciation is speciation that results when a population is separated by a physical barrier. It is also referred to as geographic speciation. Sympatric speciation is speciation that occurs without physical separation of members of the population.
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