Question

List four causes of speciation and which of these can't be a major factor in the speciation of a self pollinating plant species? Explain briefly

Answer 1

Speciation is the process of formation of new species from preexisting species. The factors responsible for speciation are:

• Geographical barrier
• Natural selection
• Genetic drift
• Large mutation

1. Geographical barrier: Geographical isolation is isolation of a species or a group of individuals from others by the means of some physical (geographical) barrier like river, mountain,big glacier etc. As the result of geographic isolation, the two species are reproductively isolated. Geographical isolation results in evolution of new species.
2. Natural selection: It is the process by which nature selects the individual which can survive in a particular kind of environment with best possible traits. The nature selects those individuals which have variations which makes them more fit than others for the given environment. Selection performed by nature, of the best suited varieties ( having favourable variations) to survive and destruction of the less suited varieties through exposure to environmental stresses results in the formation new species.
3. Genetic drift: Genetic drift may be defined as the sudden change in the frequency of the alleles of a gene in a given population. The random genetic drift may be an important factor in the formation of new species.
4. Large mutation: Mutation is the change in the DNA. The large mutation in DNA can also result in speciation.

Among the given factors, geographical isolation cannot be the major factor in speciation. This is because geographical isolation cannot prevent the transfer of pollens among the self-pollinating plant and hermaphrodite animals. Hence, geographical isolation cannot promote speciation in this case.