Actually, the world is full of high-resolution continua in species, it's just not always present. Divergence occurs due to isolation or some other factor. Hors

Actually, the world is full of high-resolution continua in species, it's just not always present. Divergence occurs due to isolation or some other factor. Horses and Zebras are different species but can interbreed. Lions and Tigers can interbreed. https://en.wikipedia.org/wiki/Hybrid_(biology) https://en.wikipedia.org/wiki/Hybrid_(biology) So the expected continuum you seek is totally there in tons of cases. It's just that there are cases where divergence gets too stark and intermediates die out. When humans choose (for conceptual and communications' sake) to identify two very similar groups as different species versus different breeds, then we call mixes "hybrids" like this. When we think it's just a little too similar and we call them "breeds" of the same species, then we don't call mixes "hybrids" as often. This is just problems with the simiplisticness of language.