Speciation : Biogeography
Speciation
Speciation is the process by which a new kind of plant or animal species is created. It occurs when a group within a population separates from other members and develops its own unique characteristics t o form a new species.
Geographical / Allopatric speciation
It is also called as allopatric speciation . It is the method by which geographical isolation stops the connection between interbreeding members of the same population.
A physical barrier, such as a mountain range or a waterway, makes it impossible for them to breed with one another. Each species develops differently based on the demands of their unique habitat or the genetic characteristics of the group that are passed onto offspring forming two different species in the long term.
Example:
The elephant population in Africa and India evolved separately forming different species of the same population.
Marsupials developed as Kangaroo in Australia, Opossum in South America, Tasmanian tiger in Tasmania
Peripatric speciation
It is a type of speciation by which populations on the edge of an ecosystem become isolated and evolve divergent lead to create a new species. It is a subtype of Allopatric speciation in which one group is much smaller than the other.
Unique characteristics of the smaller groups are passed onto future generations of the group, making those traits more unique. Thus the smaller group can be distinguished from the main group.
Example :
Drosophila has undergone an adaptive radiation into hundreds of endemic species on the Hawaiian island chain;
Parapatric speciation
When two populations live closely along adjacent geographic extent in which the population is spread over a large geographical area, it is peripatric speciation. The different habitats influence the development of different species in parapatric speciation though there is no physical barrier. Thus the species are separated by differences in the same environment.
Example
Buffalo grass can tolerate the environments affected by metal pollution. Thus unlike many grasses of the same species, it has become a unique species that grows in areas polluted by metals.
House rats in Eastern and Western Europe
Sympatric speciation
It is a typical speciation in which a variety of species are found living in a single range. In this several genotypes develop as new species, perhaps based on a different food source or characteristic, seems to have developed spontaneously.
It occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another.
Example :Various species of of insects developed and live in common space without interbreeding
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