How many generations until a new species is formed? - (May/08/2010 )

For selective breeding in mammalian sexual reproduction, about how many generations would need to pass before a new species came into being, one that could no longer successfully breed with the starting stock?

Pick a number... what do you know about selection pressure?

bob1 on May 10 2010, 01:40 AM said:

I am unfamiliar with selection pressure. In a laboratory setting it would be possible to select for individuals with a particular trait, putting selection pressure at its maximum. Being prevented by an external agent from reproducing isn´t what counts in determining whether a new species has formed, though.

If selection pressure is at its maximum, how many generations would it take, I wonder. I don´t think it is known.

It depends on the mechanism of speciation (see here). There is no way to know in advance how many generations such an event would take to occur.

To give a number, sometimes even one generation may be enough, i.e. one mutation that then via selection or building a reproductive barrier separates the populations. But this is a very, very rare event, as the mutation has to spread and not eradicated or just outnumbered in a large population.
Here is an example, with an approximately way how it could work.

Thanks for this article hobglobin. It's very interesting.