Actually, while traveling across the Mojave, I came across a crazy-looking man, who told me this riveting tale:
Once, long ago, months after the Great War, Geckos snuck into a military base that leaked FEV, like you said. Before discovering the FEV vats, however, the geckos came across a colony of ants. Having no place to stay, the geckos took up residence with the ants. Things heated up quickly, and war was quickly declared once a gecko was caught eating Arnold, one of the head ants. This war was long and hard, and many on both sides died, fighting valiantly for their race. Eventually, they both found the FEV vats. For a time, they ignored them, but once one of the ants crawled in and evolved surprisingly quickly into a giant, fire-breathing ant, the geckos were quick to take hold of the vats and use them to their advantage. The ants managed to take hold of one, and soon they were both giant, fire-breathing variants of the original race.
The end.
Nice story. but I think Ill go with the flyaway queen laying down a nest in the Mojave.. lol.