First Definitive Evidence for Chromosomal Theory: Thomas Hunt Morgan

Thomas Hunt Morgan provided the first experimental proof of the chromosomal theory through fruit fly linkage studies. The correct answer is 3. Thomas Hunt Morgan.

Correct Answer

Morgan’s 1910-1915 Drosophila experiments demonstrated sex-linked inheritance and genetic linkage, showing genes on the same chromosome (X) are inherited together unless crossing over occurs, providing concrete proof chromosomes carry hereditary factors.

Option Explanations

1. Gregor John Mendel (Incorrect)

Mendel established inheritance laws (1865) through pea plants but worked before chromosome discovery and never linked traits to chromosomes.​

2. Sutton and Boveri (Incorrect)

They proposed the chromosomal theory (1902-1903) based on cytological observations of meiosis matching Mendel’s segregation, but lacked direct experimental genetic proof.

3. Thomas Hunt Morgan (Correct)

Morgan’s white-eyed fly mutants showed X-linkage; his lab confirmed chromosomes as gene carriers via linkage maps, earning Nobel Prize (1933).

4. Hugo De Vries (Incorrect)

De Vries rediscovered Mendel’s work (1900) and proposed mutation theory, contributing to genetics but not chromosomal theory evidence.​