Mitochondrial sequences reveal a clear separation between Angolan and South African giraffe along a cryptic rift valley

Some supposedly Angolan giraffes carried the maternal DNA of South African giraffes. Their unexpected ancestry emerged in northern Botswana and northeastern Namibia, where regional identities had often been assigned from appearance and geography. Getting those identities right mattered because moving giraffes between reserves could mix populations whose evolutionary histories were still poorly understood.

Friederike Bock, Julian Fennessy and colleagues analysed mitochondrial DNA from 161 giraffes, including 102 newly sampled animals. This DNA passes from mothers to offspring, allowing the researchers to trace maternal relationships. Expanded sampling in southern Africa let them compare giraffes from previously unstudied areas with recognised Angolan and South African populations, rather than accepting the existing regional labels.

Forty-six animals sampled as Angolan giraffes instead grouped with South African maternal lineages. Central Kalahari giraffes retained Angolan ancestry, revealing a sharp geographic division where no obvious modern barrier explained it. The researchers proposed that ancient lakes, drainage changes and wetter vegetation associated with a little-visible rift system might once have separated them. That historical explanation remains a hypothesis, and maternal DNA cannot reveal the whole history of male-mediated exchange. The firm result was a changed distribution map: giraffes’ inherited maternal identities did not match the labels previously attached to their locations.