Would you like a publishable project?

Yesterday in Population Ecology I asked a question about evolution of mammalian body size on islands. Chip (my incredibly intelligent hyper Pop Ecol professor) said, "That's an excellent question, and no one has modeled it. If you want to do this, you'd have a publishable paper. It could be a chapter in your thesis!" Wow. Ok. Exciting, but also a bit intimidating. It would be really cool to do that. However, I don't see it as fitting in very well with the general trend/theme of my research interests at this point. How do you deal with that? Can you have a chapter in your thesis that has nothing (or little) to do with anything else you've done?