If any idea is a meme, is any meme an idea, and is there a direct causal relationship or is it a coincidence (or, can there be an idea that is not a meme)?
If so, and if the former, then the definition of "meme" is a synonym of "idea" and that would be that, but I don't think most people use that definition.

Note that I'm somewhat biased, loosely speaking I don't consider raw microblog quips to fit a community / subreddit / virtual space called "memes".