Speciation And Evolution - Factors Affecting

Evolution is the successive modification in inherited traits over a huge span of time, usually over generations. The theory of evolution was first proposed by an English biologist named Charles Darwin. In 1859, he mentioned about evolution in his book ‘The Origin of Species’. He noted that living organisms change their physical and anatomical structure over a long period of time for better adaptations to the changing environment. The change is by natural process and those organisms which do not adjust to it, find it difficult to survive. This put forward the concept of natural selection and Darwin called it ‘Survival of the fittest’. Speciation is an evolutionary process which resulted in natural selection. Let’s learn more about the concept speciation and factors affecting speciation.

Speciation

Speciation is defined as the formation of a new species from an existing species, either by evolution or by genetic modification.

A species is a group of organisms with similar characteristics and can interbreed to give fertile offspring. Speciation is an evolutionary process of the formation of new and distinct species. The new species are reproductively isolated from the previous species i.e., the new species can’t reproduce with the old species.

Factors Affecting Speciation

 There are several factors which lead to speciation. Two of them are:

Geographical Isolation: Due to some geographical changes few members of a species get isolated from other members. Later, this isolated group grows in a different land and eventually evolves as a new species with new adaptations according to its environment. Natural selection and genetic drift have a major role to play in this.Let’s understand this as an example.

Suppose earlier there was a species of flies living on land A. Some of them fed on dead animals. Evidently, there was a flood which washed off the dead animals and the flies feeding on them. Consequently, a few groups of flies get isolated from the other members to another land B. The species on land A and land B are too far to unite. Moreover, the environmental conditions in land B are different from those on the mainland A. The groups of flies which now live in land B start to adapt themselves according to their environmental conditions. Gradually, the individual’s structure and functions alter to give rise to a new species. This is speciation.

The new species are different from the flies in mainland A as well as from the flies who got introduced to land B by the flood. Even if this new species was reintroduced to the mainland A, they would not mate with those flies. New species start to mate amongst themselves. Thus a population of new species arrives.

Speciation

Hybridization: Hybridization is an artificial method to develop a new species. In animal husbandry, two parents from different species are mated to form a third species.

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Practise This Question

Two islands were separated from each other due to tectonic movements over a course of time. One of the islands moved towards the north pole (cold area) and other one moved towards the equator (hot area). What will happen to the rabbits living on the two islands?