In recent years, South African conservation officials have noted the appearance of sarcoid
tumour-like growths in Cape mountain zebra (Equus zebra zebra) populations. In domestic
horses (Equus ferus caballus), a genetic predisposition for this bovine papillomavirusinduced
tumour is reported. This investigation compared population genetic parameters
within tumour-affected populations in Bontebok National Park and Gariep Dam Nature
Reserve against Cape mountain zebra populations having few or no tumours in Karoo
National Park and Karoo Nature Reserve in South Africa and Hartmann’s mountain zebra
populations from Namibia. Tumour-affected populations had the lowest levels of expected
heterozygosity, gene diversity and polymorphism and highest values of internal relatedness
and homozygosity by loci but not reaching levels of significance (P = 0.05). Wright’s FIS
values indicated an overall deficit of heterozygotes in both affected and non-affected Cape
mountain zebra populations. Considerable population substructuring, as indicated by FST
values and Bayesian clustering, was revealed among all Cape mountain zebra populations.
The results provide support for current conservation policies aimed at increasing levels of
genetic diversity in isolated Cape mountain zebra populations.