What did Hugo de Vries propose as the cause of evolution based on his work on evening primrose?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Mutations
In the first decade of the twentieth century, Hugo de Vries worked on the evening primrose and brought forth the idea of mutations, that is, large differences arising suddenly in a population. He believed that mutation, and not the minor heritable variations described by Darwin, causes evolution. Since such a mutation could make a new species in one step, he called it saltation.
The other three options do not fit. Natural selection was Darwin’s mechanism of evolution, while genetic drift and gene flow are factors that change allele frequencies, as described under the Hardy-Weinberg principle. None of them was the idea de Vries drew from evening primrose.
NCERT Extract:
Mechanism of Evolution – “What is the origin of this variation and how does speciation occur? Even though Mendel had talked of inheritable ‘factors’ influencing phenotype, Darwin either ignored these observations or kept silence. 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.”