The extent, impact and management of ungulate translocations

[摘要] ENGLISH ABSTRACT: The worldwide movement of biota is of substantial concern for the conservation ofbiodiversity. The movement of species takes place at three different scales. These aretranslocations of indigenous species within their natural distribution ranges, thetranslocation of species outside their natural distribution ranges within geopoliticalboundaries (i.e. extralimital introductions) and the translocation of species outsidegeopolitical boundaries and their natural distribution ranges (i.e. extraregionalintroductions). Ungulates are extensively translocated at each of these scales and eachscale of translocation is expected to have different impacts on biodiversity. Ungulatesare translocated for conservation purposes such as reintroducing species to placeswhere they have previously gone extinct and to mitigate inbreeding in small, isolatedpopulations. Ungulates are also extensively translocated for economic andrecreational reasons, such as for sport hunting. Translocations for sport huntinginclude indigenous, extralimital and extraregional species. Concerns for translocationsof indigenous species are largely for the loss of genetic diversity through the mixingof genetically distinct populations, and concerns for extralimital and extraregionaltranslocations are for impacts on indigenous biodiversity such as through herbivory,competition, hybridization and disease transmission. This thesis investigates theextent of ungulate introductions globally and at a finer resolution in South Africa. Itinvestigates the pathways, drivers and impacts of ungulate introductions and it alsoinvestigates the use of surrogates for genetic distinctiveness for advising thetranslocation of indigenous ungulates. The study finds that ungulate translocationshave been extensive and have lead to the homogenization of ungulate assemblages incountries globally and at a quarter-degree grid-cell resolution in South Africa. Zooswere identified as a potential introduction pathway for extraregional ungulatesglobally and in South Africa extraregional introductions have made ungulateassemblages more different; whereas large numbers of extralimital introductions havemade ungulate assemblages more similar. The homogenization of ungulate species inSouth Africa has increased with time, due to increased numbers of translocations,particularly of extralimital species. In South Africa translocations have most recentlybeen made to high-income areas with high human population density and highlivestock density; whereas in the 1960s ungulates were introduced to areas species poor for indigenous ungulates and marginal for livestock. In South Africa, longdistance translocations of indigenous species extralimitally has resulted in extensiverange expansions of a magnitude greater than predicted range changes as a result ofpredicted climate change. When the use of surrogates of genetic distinctiveness foradvising translocations was investigated for Africa, the East African rift valley wasfound to be important in delineating genetic distinctiveness and translocations acrossthis feature should be prevented. Major rivers in Africa also showed potential fordelineating genetic distinctiveness in ungulates, but relevant phylogeographic data areneeded to confirm this. Sufficient evidence for the impacts of non-indigenousungulates on biodiversity both in South Africa and globally is lacking despitesubstantial concern for their impacts. It is suggested that to demonstrate the impacts ofnon-indigenous ungulates exclosure and enclosure experiments should be used and population declines in indigenous species should be shown.

[发布机构] Stellenbosch University