The two key concepts of Darwinian theory of evolution are:

The correct answer is Option (2) → Branching descent and natural selection

Darwin’s theory of evolution rests on two ideas. Branching descent means that all life forms come from common ancestors, and the lines split like the branches of a tree. Natural selection means that organisms better adapted to their environment survive and leave more offspring, because their useful traits are inherited.

(1) Saltation and gene pool — Incorrect. Saltation is a single large mutation that makes a new species at once. It was proposed by Hugo de Vries, and Darwin believed in small, gradual variations. The gene pool is a term of population genetics.

(2) Branching descent and natural selection — Correct. These are the two key concepts of the theory.

(3) Genetic drift and genetic recombination — Incorrect. These are processes that bring variation. Darwin did not know about them.

(4) Gene flow and mutation — Incorrect. These are factors that change allele frequencies in a population. They are not Darwin’s key concepts.

Note: A similar question was also asked in CUET (UG) 2026 on 22-05-2026 (Slot 1).

NCERT Extract:
Biological Evolution – “… Branching descent and natural selection are the two key concepts of Darwinian Theory of Evolution (Figures 6.7 and 6.8).”