The Great Debate.

[pineapplebunnybounce]

A species... yes that is a good question. I'd say a dog is a species... or dog like creatures, I can see how a wolf dingo dog coyote are all very similar and evolution could create those differences.
But the problem is where did the first dog come from... a fish, out of the oceans somehow? I find that leap hard to comprehend, that is the issue I see with modern evolution theory.

I've briefly explained the concept of a species in my post right before yours. If you are interested in this subject, I highly recommend Richard Dawkins' "The Ancestor's Tale". He explains the human need for a discontinuities and order and how that conflicts with reality better than any other explanation I've read. It is also very well written and very enjoyable and you'll learn about a lot of new species ( I mean creatures you've never heard of).

ETA: The leap you perceive exists because the ones that would fill the gap from the modern species to their common ancestors are extinct. But a lot of their fossils have been found. It's basically very small changes over a long period of time (a very very long period of time) and then all the earlier ones died. Leaving you with modern species that don't look like each other.