A genomic exploration of the possible de-extirpation of the Zanzibar leopard

The recently extirpated Zanzibar leopard was the only known African leopard (Panthera pardus spp.) population restricted exclusively to a major island habitat. Although its demise was driven through habitat change and conflict with humans, given its role as a keystone species for the Zanzibar Archipelago, its potential reintroduction might offer a means for helping preserve the natural biodiversity of its former habitat. Whether this is feasible, however, would be contingent on both whether closely related source populations can be identified on mainland Africa, and whether the Zanzibar form exhibited any special adaptations that might need to be considered when choosing such a source. In light of these questions, we genomically profiled two of the six known historic specimens, to explore whether they represent a realistic candidate for de-extirpation through reintroduction. Our analyses indicate that despite its geographic separation, the Zanzibar leopard shared a close genetic relationship with mainland East African individuals. Furthermore, although its uniqueness as an island population was emphasised by genomic signatures of high inbreeding and increased mutation load, the latter similar to the level of the critically endangered Amur leopard (P. p. orientalis), we find no evidence of positive selection unique to Zanzibar. We therefore conclude that should attempts to restore leopards to Zanzibar be planned, then mainland East African leopards would provide a suitable gene pool, whether using genetic engineering or conventional rewilding approaches.