The six subspecies of plains zebras (Equus quagga) that roam the savannas of southern and eastern Africa have been defined on the basis of head shape and the pattern of the animals’ stripes. A new study published online this week in Nature Ecology & Evolution, however, reveals genetic differences between these subspecies that do not match this morphological classification.
Zebras are threatened by habitat loss and hunting. Conservation agencies currently use the morphological subspecies classification to assess zebra populations, but Casper-Emil Pedersen and colleagues suggest that this should be revised to reflect their genetic findings.
The authors performed genome-wide analyses of 59 plains zebras, as well as three mountain zebras, and three Grevy’s zebras. On the basis of geographical location and genetic differences, they identify nine existing populations of plains zebras, only two of which overlap with the current morphological subspecies designation. The authors’ modelling suggests that the ancestors of today’s diverse zebra populations probably lived in the Zambezi - Okavango wetland area of southern Africa. Their analysis also confirms that the extinct ‘quagga’ (Equus quagga quagga) was another variant of the plains zebra and not a species in its own right.
Based on their findings, the authors conclude that ensuring gene flow between these diverse zebra populations is essential for the species’ survival, and this will be best achieved through conservation strategies that keep zebra habitats connected, rather than divided up.