In an earlier response to someone elses question you said:
"I accept that such coevolution is the most likely (and indeed only
supported) idea. And since it's been observed in some systems and is
plausible in others, it's reasonable to assume that is what is
happening. If I go to a factory and see a BWM assembled by robots, I
don't have to see every factory in the world manufacturing every product
to accept that it is possible to build both complex and simple things
in this way."
Just wondering what the systems it has been observed in were? It would be useful when dealing with questions to be able to point to a specific example (debating with creationist friends is tiring)!