Question

The plant on which Hugo de Vries based his evolution theory is
A. Antirrhinum majus
B. Lathyrus odoratus
C. Oenothera Lamarckiana/Evening Primrose
D. Pisum sativum

Answer 1

Hint: Heredity is the transmission of characters from parent to offspring is called heredity. All the individuals of the same species are not similar but have some differences. Differences are called variation. Variation may be continuous or discontinuous. Mutation is a discontinuous source of variation.

Complete answer:
Hugo de Vries (1901) put forward mutation theory. Mutation is the sudden and permanent heritable change in genetic material of an organism. Mutation theory helped in the study of Evolution. According to his theory, evolution is a jerky process where new species are formed by mutations (discontinuous variations). Mutation had provided raw material for evolution.
Hugo De Vries conducted his experiments on the plant Oenothera lamarckiana, the common name of this plant is “Evening Primrose”. When Oenothera lamarckiana was self-pollinated and seeds were collected. Its seeds were allowed to grow, the majority of F1-plants were similar to the parents, but a few plants were different from the parent plant.
The plants with variations were also self-pollinated and their seeds were sown, the majority of the plants were similar to the parents while a few were again shown variation from their parents. Similar experiments were done for several generations, and the same result appeared. These plants appeared to be new species.
Based on his experiments, Hugo de Vries suggested that new inherited characteristics may appear suddenly without any previous indication of their presence in the race. He observed 834 mutations in 54343 plants of Oenothera lamarckiana. He believed that mutation causes evolution. The minor heritable variations as mentioned by Darwin does not cause evolution because Darwin’s variations are small and directional. Whereas, mutations are random and directionless.

Thus, Option C. Oenothera Lamarckiana/Evening Primrose is the correct answer.

Note: According to Hugo de Vries believed that mutation is the reason for the formation of new species by single step large mutation, whereas Darwin believed evolution is a gradual process.