The diagram below shows how a human might
create a new species.
In this case a farmer notices that a sheep with short, curled legs has been
born (sheep with black box). The black box means the sheep has one of these
new, mutated genes which causes the short legs. The farmer then breeds a normal
sheep with the "mutant" sheep. They have some normal offspring and
some more mutant sheep.
The farmer then mates 2 "mutant" sheep to obtain mostly short sheep
with a few normal sheep still occuring. Eventually he eliminates the long leg
trait from this line of sheep and now has purebred sheep with all their leg
genes coding for short legs. This new breed of sheep are now known as Ancon
breed sheep.
Long & Slichter