Question

Mutations are ___A___ while Darwinian variations are ___B___.

• A. A- random and continuous, B- discontinuous
• B. A- minor and directional, B- major and directionless
• C. A- small and directionless, B- random and directional
• D. A- random and directionless, B- small and directional

Answer 1

The correct option is D A- random and directionless, B- small and directional

Hugo de Vries, based on his work on Oenothera lamarckiana or evening primrose, proposed the mutation theory. In this theory, he explained that new species evolve by sudden and distinct heritable changes called mutations.

These mutations can occur at any time hence are random and can be useful, harmful or have no effects at all on the organisms hence are directionless.

As the mutations are produced occasionally without prior precedent, they are termed as discontinuous heritable changes in the genetic material.

On the other hand, Darwin’s theory states that new variations appear in every generation (continuous) and such small variations accumulate over several generations by natural selection until the offspring become significantly different, thus evolving into a new species. Thus, Darwinian variations were considered small and directional.

Hugo de Vries believed that it is mutation which causes evolution and not the minor variations (heritable) that Darwin discussed in his theory.

Mutations are random and directionless while Darwinian variations are small and directional.