Lets put this hypothesis:
Imagine we find a planet similar to earth and we send a bunch of colonists there to populate that planet, then, some misshap prevents them from communicating with earth or return. After a few milions of years, people on earth and the people on that planet would not be able to have children between themselves, or if they could, it would be a sterile hybrid. Speciation would occur if genetic transference is ceased between 2 populations. Look at the horse and the donkey, 2 different species and they can interbreed, but that offspring (the mule) is sterile, it can't have little 'mules'.
Imagine we find a planet similar to earth and we send a bunch of colonists there to populate that planet, then, some misshap prevents them from communicating with earth or return. After a few milions of years, people on earth and the people on that planet would not be able to have children between themselves, or if they could, it would be a sterile hybrid. Speciation would occur if genetic transference is ceased between 2 populations. Look at the horse and the donkey, 2 different species and they can interbreed, but that offspring (the mule) is sterile, it can't have little 'mules'.
