10. Are mountain and plains zebra hybridising in north-west Namibia?

This chapter focuses on interactions between two animal species critical to the ecosystems of Etosha-Kunene, namely mountain zebra (Equus zebra, specifically the subspecies E. z. hartmannae) and plains zebra (E. quagga, specifically the subspecies E. q. burchellii). Large herbivore species are increasingly restricted to fenced protected areas with artificial waterpoints, a situation that limits their opportunities for dispersal and access to natural water sources. This restricted movement may lead to genetic consequences including disruption of gene flow, inflation of “inbreeding”, and the loss of rare alleles supporting local adaptation and genetic fitness. In Namibia’s large protected area of Etosha National Park, mountain zebra are restricted to the dolomite ridges in the far western section of the park while plains zebra occur throughout the park. Historically, the overlap in range of the two zebra species was limited, as plains zebra confined their movements to the southern and eastern edges of the Etosha Pan during the dry season, and to the open plains west of the Pan during the rainy season. Due to fencing and new waterpoint creation, this extended overlap of these two previously geographically separated species creates a potential conservation problem in the form of hybridisation between the two species. This chapter reviews what is known about the hybridisation of these two species, and considers implications for conservation and for future research.