The Ambsystoma salamanders of the great lakes region have the most peculiar mating system.. they are all females, but they steal the genomes from other related species to aid in reproduction. This "kleptogenesis" is ancient, probably originating 5 million years ago. This makes it a stable reproductive strategy but it defies everything the text books tell us about species boundaries. In this episode Prof Katty Greenwald and I talk about what makes a species and how vague the term can really be.