Originally posted by @moonbus
A new species has emerged and we saw it happen.
It says "...This new finch population is sufficiently different in form and habits to the native birds, as to be marked out as a new species, and individuals from the different populations don't interbreed...
So this new species is at a result of hybridization between two related species but then followed by rapid further changes via evolution so that they are now rapidly become so
different in characteristics from either of their two parent species that they no longer interbred with either of their two parent species thus, by any
reasonable definition of species, they are now a new
This observation of such a rapid species change is yet further evidence in support of punctuated equilibrium (see https://en.wikipedia.org/wiki/Punctuated_equilibrium) although the evidence for punctuated equilibrium was already so strong that it really was already scientific fact.