Regarding the water dragon...a female can lay eggs without being mated just like some chameleons do. It doesn't usually happen until the female is two or three. They can also develop MBD like chameleons can.
I use the same supplementing and gutloading I do for chameleons for water dragons. I also give them a "salad" two of three times a week using the same greens and veggies that I use for gutloading...along with a small amount of fruit ( apple, berries, melon, pear, etc )
There has been so much trouble with eggbinding in chameleons that there has been a study going on here in Ontario for several years now to determine what to do about it...including possible "birth control".