Q.How does Mutation theory of De Vries differ from Lamarck and Darwin’s view in the origin of new species.

Step 1. Lamarck's model of change is gradual: organs enlarge or degenerate slowly through repeated use/disuse across an organism's lifetime, with these lifetime changes then supposedly passed on and compounded over generations.

Step 2. Darwin's model is likewise gradual: he emphasised small, continuously varying differences between individuals, on which natural selection acts slowly, generation after generation, to shift a population's characteristics.

Step 3. Hugo de Vries, based on his observations of sudden, discontinuous variation in Oenothera lamarckiana, proposed instead that new species arise abruptly, through large mutations that produce a fully formed new type in a single step, with no intermediate forms bridging it to the parent type. …

Contrast the tempo of change each theory proposes — sudden/discontinuous (de Vries) versus …

• Treating Lamarck's and Darwin's views as opposed to each other on this specific point, when in fact both agree on gradualism (they differ on the mechanism of inheritance, not on tempo). …