who was the first to do a study on this subject?
Ronald Fisher
Genetic drift
Ronald Fisher, who explained natural selection using Mendelian genetics,
when gene flow occurs it’s effect is the opposite of genetic drift because UNANSWERABLE
wiki:13415162
Genetic drift [SEP] Introduction
When there are few copies of an allele, the effect of genetic drift is larger, and when there are many copies the effect is smaller. In the middle of the 20th century, vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian genetics, held the view that genetic drift plays at the most a minor role in evolution, and this remained the dominant view for several decades. In 1968, population geneticist Motoo Kimura rekindled the debate with his neutral theory of molecular evolution, which claims that most instances where a genetic change spreads across a population (although not necessarily changes in phenotypes) are caused by genetic drift acting on neutral mutations.