Single step large mutations causing speciation are called:

The correct answer is Option (2) → Saltation

Option (1) Founders' Effect — Incorrect. The founder effect is a change in allele frequency in a small new population.

Option (2) Saltation — Correct. Hugo de Vries said that large mutations appearing in a single step cause speciation. He called this saltation, in contrast to Darwin’s gradual small variations.

Option (3) Genetic Drift — Incorrect. Genetic drift is a chance change in allele frequency.

Option (4) Gene flow — Incorrect. Gene flow is the movement of alleles between populations.

Note: A similar question was also asked in CUET (UG) 2023 on 26-05-2023 (Slot 3).

NCERT Extract:
Mechanism of Evolution – “… In the first decade of twentieth century, Hugo deVries based on his work on evening primrose brought forth the idea of mutations – large difference arising suddenly in a population. He believed that it is mutation which causes evolution and not the minor variations (heritable) that Darwin talked about. Mutations are random and directionless while Darwinian variations are small and directional. Evolution for Darwin was gradual while deVries believed mutation caused speciation and hence called it saltation (single step large mutation).”