The point is, you don't get that high numbers by genetic drift alone.
Such a spread would be too rapid to have occurred by genetic drift, and must therefore be the result of selection.
Gone is the initiative of President's first four years, they say, replaced by drift and a reluctance to challenge Senate conservatives.
These individuals seem to be a small gene pool, derived from the continental populations, which is slowly creating a new type by genetic drift.
It is thought to have achieved its present distribution largely by continental drift rather than dispersal across ocean gaps.
In particular, he developed a stochastic theory for the evolution of quantitative traits by genetic drift and natural selection.
The Himalayas are fold mountains formed millions of years ago by continental drift.
New viruses can also emerge by drift.
This could happen by genetic drift if the population is small enough.
"Instead, the spore apparently moves by slow drift through a morasmal aggregate."