A comparative approach for species delimitation based on multiple methods of multi-locus DNA sequence analysis: A case study of the genus Giraffa (Mammalia, Cetartiodactyla)

The same giraffe DNA can produce different answers about how many species exist. Genetic differences can separate populations without necessarily making them different species. That distinction matters when researchers use DNA to decide which giraffe groups should receive separate conservation assessments.

Alice Petzold and Alexandre Hassanin reanalysed available sequences representing 21 nuclear regions from 137 giraffes, alongside mitochondrial sequences from 507 individuals. They compared methods that reconstruct family trees, group genetically similar animals or model how populations diverged. The investigation revisited evidence used in earlier work supporting four species, testing how the choice of method and settings affected the boundaries drawn.

Across analyses, the possible classifications ranged from two to six species. The authors favoured three: a northern group including reticulated giraffes, a southern group and a Masai group. These divisions had stronger agreement across approaches and shared diagnostic mutations in the regions examined. Their conclusion is an interpretation of a limited set of genetic markers, not a final census of giraffe species; some methods supported finer divisions. The study exposes why species debates can persist even when researchers share the same data: detecting genetic structure and deciding that it represents reproductive separation are related, but different, tasks.