Step 1: Concept Overview:
Neo-Darwinism, or the modern evolutionary synthesis, combines Darwin's natural selection theory with Mendel's genetics. This question asks us to identify the key individuals who established the mathematical and theoretical basis for this synthesis in the early 20th century by creating population genetics.
Step 2: Detailed Explanation:
- A. R.A. Fisher, B. Sewall Wright, and D. J.B.S. Haldane are widely acknowledged as the primary founders of theoretical population genetics. Independently, in the 1920s and 1930s, they mathematically demonstrated how Mendelian inheritance and natural selection could interact to drive evolutionary change.
- C. Gregor Mendel, a 19th-century pioneer, discovered the fundamental principles of heredity. His work was essential for the modern synthesis, but he predates it and wasn't an architect of it. Neo-Darwinism integrates his work with Darwin's, a task completed by later scientists.
Step 3: Final Answer:
R.A. Fisher, Sewall Wright, and J.B.S. Haldane founded theoretical population genetics and developed neo-Darwinism. Therefore, the correct option includes A, B, and D.