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

(a) Speciation: It is evolution of a new species from pre-existing species.
(l) Occurring due to accumulation of variations.
(ii) By processes like genetic drift/geographical barriers like mountains, rivers etc,. leading to incapability to reproduce amongst themseir.es in the population.
(b) Natural selection:
(l) Change in frequency of some genes in a population.
(ii) Which give survival advantage to a species from elimination.
(lii) Example – In a population of beetles, a new variation (green colour) get survival benefit/ advantage to red beetles whereas other red perishes.