Who experimentally demonstrated “Mutations occur randomly”?​​

Correct option is C

Salvador Luria and Max Delbrück experimentally demonstrated that mutations occur randomly through their Luria-Delbrück Fluctuation Test (1943). This experiment provided crucial evidence supporting the random mutation hypothesis rather than the directed mutation hypothesis.

Luria-Delbrück Fluctuation Test (1943):

1. They used bacteriophage T1 and E. coli bacteria to test whether mutations arise in response to selection or occur randomly.
2. If mutations were directed (adaptive) by environmental factors, each culture would have roughly the same number of resistant colonies.
3. If mutations were random, the number of resistant colonies would fluctuate significantly across different cultures.
4. Their results showed high variability in resistance colony numbers, supporting random mutation.

This experiment became a cornerstone of modern evolutionary biology and genetics, proving that mutations are pre-existing events, not induced by environmental stress.

Information Booster:

1. Random mutations occur before exposure to selection pressure.
2. Selection does not create mutations, but rather selects for pre-existing mutations that provide survival advantages.
3. Luria and Delbrück won the Nobel Prize in 1969 for their contributions to bacterial genetics and virus replication.
4. Mutation rates can be calculated using the Poisson distribution, which was applied in their study.
5. Their experiment was one of the first demonstrations of Darwinian evolution at the microbial level.
6. This study supported natural selection, showing that beneficial mutations arise spontaneously rather than as a response to environmental challenges.