If by "magic" you mean the established science called "genetics", then yes.
When the chromosomal information of two lineages becomes too disparate, the ability to interbreed is lost.
And what has mulism got to do with it.
A mule is the offspring of a species known as Equus caballus and another species known as Equus asinus - the two species are very closely related and evolutionists consider them to have a common acnestor.
However, when they mate, the union - called a mule or a hinny - rarely produces offspring and these offspring are almost always unable to reproduce (there are fewer than 100 documented cases of mules reproducing and one documented case of the offspring of mules reproducing in recorded history).
This demonstrates that when a certain threshhold of genetic diversity or mutation is reached, the ability to interbreed is lost.
I was going to make a joke about West Virginia here, but I'll refrain.
Completely irrelevant to the point I was making.
Once speciation has occurred, the interbreeding finally stops.
The “macro-evolution” folk say changes cannot ever reach that stage.
I want to know their proposed mechanism for stopping.