Question

According to Hugo De Vries, speciation is due to

• A. Accumulation of small variations
• B. Intraspecific breeding
• C. Interspecific breeding
• D. Single-step large mutation

Hint:

Darwin = Gradual, small, directional variations over long periods.
De Vries = Sudden, large, random, directionless mutations (Saltation) in a single step.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept: Different evolutionary biologists historically proposed different mechanisms for how new species arise, a process known as speciation.
Step 2: Key Formula or Approach: Differentiate the evolutionary mechanism proposed by Hugo de Vries from that proposed by Charles Darwin.
Step 3: Detailed Explanation: Charles Darwin believed that evolution was a slow, gradual process driven by natural selection acting on minor, heritable variations accumulated over many generations.
In stark contrast, Hugo de Vries based his theory on his extensive experiments with evening primrose (Oenothera lamarckiana).
He proposed that new species arise suddenly in a single generation due to large, sudden, unpredictable genetic changes.
He specifically coined the term "saltation" to describe a single-step large mutation that leads directly to speciation, bypassing the need for gradual accumulation.
Step 4: Final Answer: According to de Vries, speciation is driven by a single-step large mutation.