Neal Stephenson's _Seven Eves_ ends up with several distinct branches of humanity. It was a necessary adaptation to a population bottleneck -- after a global ap

Neal Stephenson's _Seven Eves_ ends up with several distinct branches of humanity. It was a necessary adaptation to a population bottleneck -- after a global apocalypse there were only 7 living women and no men or sperm, but they did have a genetics lab. So they cloned themselves with some small changes to avoid inbreeding. Some of the changes weren't so small. Some of the populations did well, some were strange, and some were constantly warring. So not quite "positive", but not gratuitously negative either.