Comment Re:What about mitochondrial DNA? (Score 2) 154
The endosymbiotic theory suggests that mitochondria are--or at least were--a separate species themselves. That they developed from bacteria co-opted by other cells as power plants, eventually becoming the stripped-down symbionts we know today. It would explain why they have their own DNA, and I'd say it would make them (mostly) irrelevant to determination of the species they inhabit.