Simplify the following text for a Grade 12 native English-speaking person.
Original: Following the rediscovery of Mendelian inheritance in 1900 , Morgan 's research moved to the study of mutation in the fruit fly Drosophila melanogaster .
Simplified: Following the rediscovery of Mendelian inheritance in 1900 , Morgan 's research moved to the fruit fly Drosophila melanogaster .