How fast can speciation occur?

Answer 1

You may not know it, but you have a tiger by the tail here.

The problem is that the concept of 'species' is not defined with perfect clarity. Even biologists often use slightly different definitions of the term, each with their own implications and meaning. And even some of the strictest definitions of species may not apply at all to certain kinds of organisms.

For example, if a species is a population that can interbreed to produce offspring, then horses and donkeys are one species, while each asexual bacterium is a separate species. And no biologist is going to go around trying to cross-breed billions of possible species to see if they really are.

A more practical definition might be that if a population seems to be isolated and can be determined to be distinct in some way, then it's a species. But that means that someone might assemble a species in just a few minutes by locking all the blue-eyed people in a room or something.

Undoubtedly we have observed adaptation and natural (and artificial) selection copiously. Whether we have observed even ONE case of speciation in the thousands of years for which we have records is a much more protracted debate, as I hope you can imagine.

Answer 2

Completely depends on the type of organism. Certain bacteria can display speciation within hours.

Answer 3

chlaxman17 is right on. Bacteria can exhibit evolution in hours. Plants are famous for speciating in one generation with the duplication and change in number of chromosomes (polyploidy) that prohibits reproduction with the parent plants and others of their species.

Answer 4

Well it depends what species you are talking about. Usually at least a dozen generations to really see a difference. Depends also on how strong the driving force is.