National Zoological Garden, South African National Biodiversity Institute, Pretoria, South Africa.
Department of Genetics, University of the Free State, Bloemfontein, South Africa.
PLoS One. 2019 Jul 31;14(7):e0220331. doi: 10.1371/journal.pone.0220331. eCollection 2019.
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.
海角山斑马（Equus zebra zebra）是南非特有的山斑马亚种。在 20 世纪初，海角山斑马几乎灭绝，但其数量已恢复到超过 4800 只。然而，它们的长期生存仍然面临威胁。先前的一项研究报告称，海角山斑马在三个残余种群中的遗传多样性较低，需要采取紧急的保护管理措施来降低进一步丧失的风险。由于这些建议基本上没有得到重视，因此我们在十五年后进行了本研究，以确定管理对三个关键种群遗传多样性的影响。我们的研究结果表明，海角山斑马的种群中存在大量的杂合性丧失。在德霍普自然保护区（De Hoop Nature Reserve），预期杂合度从 0.385 降至 0.297，下降了 22.85%，情况最为严重。这令人震惊，因为德霍普自然保护区以前被认为是遗传多样性最高的种群，因为它的创始种群来自三个残余种群中的两个。此外，我们还观察到所有种群的多个特有等位基因完全丢失，以及亚种间遗传结构的相关减少。这些损失可能导致近交衰退，降低海角山斑马的进化潜力。我们建议立即实施基于证据的遗传管理和监测，以防止进一步的损失，这可能危及海角山斑马的长期生存，特别是在面临栖息地和气候变化以及新兴疾病的情况下。
