This high gloss German commercial for Saturn electronics is wonderful eye candy. Everything I've seen in technology convinces me that autonomous robots are an inevitability. And once launched, self-guided robots will no doubt "evolve" -- although not by natural selection.
The chief question is how much will robots look like animals, or humans? Because they live on Earth and have to deal with us at our scale and all the natural forces at that scale, they will tend to look familiar. Gravity, air resistance, torque and friction, for examples, are inescapable common problems which tend to steer the design of robots to common solutions. Like animals they may have either two or four legs, stereoscopic eyes, tubular insides, hands, etc. To the extant that some robots will do the kind of work that we have used animals for (such as transportation, hauling) those robots will converge toward animal forms.
But most of the work we want done by robots is work we humans and animals are probably not designed for, therefore those robots will tend to diverge from animal forms. The ones we interact with most will also tend to our form simply for communication reasons. The rest will evolve into their own alien forms. I suspect that after several hundred years we'll see a full-blown taxonomy of "natural" robot genres. You can think of airplanes (once they are autonomously piloted) as an example of one class of robot species. You see one and say, that's an airplanebot.
There will be fish bots, crab-like bots, mole-ish bots, ant bots, to start the list with animal analogs. Better said would be creep bots, crawl bots, scrub bots, sneak bots, lube bots, and so on.
And we'd have two larger categories: domesticated bots and feral bots. Domesticated bots come home to roost, and to be breed by humans. Feral ones are out on their own. They find their own sources of energy, self-repair, and high-jack some means to reproduce. There may be a day in the far distant future when one could scramble over a junk yard heap and find some kind of scavenger bot. Not Wall-e exactly, but some more insect-like contraption that is able to scrape together enough power to survive and breed. The first will most likely be more like a plant than animal.
Collecting them will start out as an kid's hobby, and the realm of amateurs. Eventually science will pay attention to this emerging taxonomy.