Credit: © Wilfred / Fotolia
If the evolution of superbugs is not enough the following article should help. The following quote identifies why this is an example of speciation.
"The offspring were also reproductively isolated because their song, which is used to attract mates, was unusual and failed to attract females from the resident species"
https://www.sciencedaily.com/releases/2017/11/171124084320.htm
Is speciation the same as evolution?
Seems like 'not being able to breed with x' isn't much of an upgrade?
Biologist's definition of species is just that. When the two cannot mate then they are different species. Speciation is the first step as the decedents of the new species become/evolve increasingly different from the original.