Whole-genome analysis of giraffe supports four distinct species

Fifty giraffe genomes revealed four separately evolving species. The familiar long-necked animal had usually been classified as one species with regional subspecies, despite earlier genetic evidence for four. Giraffes from different groups could interbreed in captivity, but that did not establish how their wild populations had evolved or how often they exchanged genes.

Raphael Coimbra, Sven Winter and colleagues analysed genomes representing every traditionally recognised subspecies. They compared genetic variation across 50 giraffes, including wild and captive animals, and assembled a reference genome from a male Kordofan giraffe. They reconstructed relationships using many separate stretches of DNA, then examined ancestry, past population changes and signs of inbreeding to test whether different approaches told the same story.

The main analyses consistently separated northern, reticulated, Masai and southern giraffes. Their estimated splits dated to roughly 230,000–370,000 years ago, and each lineage had a distinct demographic history. Some captive reticulated giraffes showed mixed ancestry, so the result was not evidence that interbreeding is impossible. Rather, the genomes supported four lineages evolving largely separately. Treating all giraffes as interchangeable would overlook that history: conserving the animal’s full diversity means protecting each of those branches, not merely maintaining a continent-wide total.