Is there a demonstrable species that went through mutation breeding and through successive generations it drifted so far away from its initial parent species that it can't breed with them anymore? (I assume it would need to be able to breed with intermediate generations though). Also by "demonstrable" I mean a case where we can directly demonstrate this process by starting from a parent species to a new species and not establish this relationship by looking back (like observing the connection between corn and teosinte through genetic information).
Edit: I'm mainly curious about postmating/post- zygotic reproductive isolation. As I understand, the timescale of us is not enough to observe that kind of speciation (we can either directly observe the start of the isolation or the end of it but not both), that's why I'm curious about whether induced mutation could speed up the process enough to directly demonstrate speciation by the most difficult to achieve definition.
I have checked the thread Have we ever observed two drosophila lineages that evolved reproductive isolation in labs? but it seems to me that those results only shows premating isolation.
I have checked: Sexual and postmating reproductive isolation between allopatric Drosophila montana populations suggest speciation potential article which says, that postmating barriers observed may be due to postcopulatory-prezygotic mechanisms.
Thank you for the corrections, Im reading into Examples of creating a new animal species by humans