Can reptiles lay eggs without a male?

There have been some weird studies with amphibians, frogs mostly, that show than can change sex after becoming an adult completely naturally, and this has lead to speculation of weather a frog may be able to fertilize it's own eggs. Most amphibian eggs are fertilized outside the body, whereas reptile eggs, in both oviparous & viviparous species, must be fertilized inside the mother, similar to birds.