Explain the following.
(a) Speciation
(b) Natural Selection

(a) Speciation is defined as the process by which new species are formed in the course of evolution. Reproductive isolation and geographical isolation are two important processes that lead to speciation. In speciation, a single evolutionary lineage gets split up into two or more independent lineages which are genetically different.

(b) Natural selection states that the organisms which are fit to survive in the existing environment reproduce and increase in number while other die and perish away. Certain changes take place in the organisms which helps it adapt better to a particular environmental condition and these variation are passed to next generation increasing their chances of survival than the others. This theory was given by Charles Darwin and is based on survival of fittest.