Explain the terms: (i) Speciation (ii) Natural selection

Explain the terms:
(i) Speciation
(ii) Natural selection

(i) Speciation: It refers to the process of formation of new species that develop from existing species.
Important factors that lead to formation of new species:

  • Geographical isolation of a population caused by various types of barriers like mountain ranges, rivers, sea etc. Geographical isolation leads to reproductive isolation due to that there is no flow of genes between separated groups of
  • population.
  • Genetic drift: It is caused by drastic changes in frequencies of particular genes by chance alone.
  • Variations: It is caused in individuals due to natural selection.

(ii) Natural selection: Natural selection is “process of evolution of a species whereby characteristics that help individual organisms to survive and reproduce are passed on to their, off springs and those characteristics which do not help are not passed on.” It was suggested by Charles Darwin.