When an electron goes from one energy level to another it doesn't do so gradually, it jumps when some 'preset' threshold of energy is reached. I suspect a similar thing occurs with species, but I'm sent for six to see how it could happen. Patterns, macro processes, are the way Nature appears to express. I'd like to comprehend the large pattern process involved in species differentiation/evolution of life on planet Earth ... I think I apprehend the genetic process involved in expression of species and even perhaps the 'cause of different expression for organisms'. Perhaps I've gone too far already in trusting civil discussion ...
Something like this happens occasionally with plants. Chromosome duplication.
However it can't possibly account for a large percentage of speciation, or cells would be the size of planets.
The speciation we actually observe happens rather slowly by our standards, although it could be an eyeblink by geologic standards. It takes 50 years or so to make a dog variety or to produce a tame fox.
These can involve rather dramatic changes in morphology.