Lessons for conservation management: Monitoring temporal changes in genetic diversity of Cape mountain zebra (Equus zebra zebra)

The Cape mountain zebra (Equus zebra zebra) is a subspecies of mountain zebra endemic
to South Africa. The Cape mountain zebra experienced near extinction in the early 1900’s
and their numbers have since recovered to more than 4,800 individuals. However, there are
still threats to their long-term persistence. A previous study reported that Cape mountain
zebra had low genetic diversity in three relict populations and that urgent conservation management actions were needed to mitigate the risk of further loss. As these suggestions went
largely unheeded, we undertook the present study, fifteen years later to determine the
impact of management on genetic diversity in three key populations. Our results show a
substantial loss of heterozygosity across the Cape mountain zebra populations studied. The
most severe losses occurred at De Hoop Nature Reserve where expected heterozygosity
reduced by 22.85% from 0.385 to 0.297. This is alarming, as the De Hoop Nature Reserve
was previously identified as the most genetically diverse population owing to its founders
originating from two of the three remaining relict stocks. Furthermore, we observed a complete loss of multiple private alleles from all populations, and a related reduction in genetic
structure across the subspecies. These losses could lead to inbreeding depression and
reduce the evolutionary potential of the Cape mountain zebra. We recommend immediate
implementation of evidence-based genetic management and monitoring to prevent further
losses, which could jeopardise the long term survival of Cape mountain zebra, especially in
the face of habitat and climate change and emerging diseases.