1: Proc Natl Acad Sci U S A. 1966 Apr;55(4):727-33. Links
Spontaneous origin of an incipient species in the Drosophila paulistorum complex.Dobzhansky T, Pavlovsky O.
PMID: 5219677 [PubMed - indexed for MEDLINE]
PMCID: PMC224220
Maybe your source doesn’t know as much as you suppose.
Maybe your source doesn’t.
Hank