South Africa as a Donor of Alien Animals

Abstract

This review provides the first assessment of animal species that are native to South Africa and invasive elsewhere in the world. While around a twelfth of all naturalised plants in the world are native to South Africa, there are very few examples of South African native marine, terrestrial, or freshwater animals becoming invasive elsewhere. We provide a narrative of each of the 34 cases that we could find. Three of these species, the Common Waxbill, Estrilda astrild, the Mozambique Tilapia, Oreochromis mossambicus and the African Clawed Frog, Xenopus laevis, were widely traded, and introduced on several continents with invasive populations becoming the subject of substantial research. Most other species are poorly documented in the literature such that it is often not known whether South African populations are the source of invasions. These species demonstrate the same trend in pathways of animals entering South Africa, moving from deliberate to accidental through time. The role of mavericks, individuals whose deliberate actions wilfully facilitate invasions, is highlighted. While South Africa has acted as an important bridgehead for the invasions of forestry pests, crayfish, fish and amphibians on the continent, it is clearly not a major donor of animal invasions, but rather a recipient. This could be due to South African ecosystems being fundamentally more invasible, or South African fauna showing reduced invasiveness, though it is likely that substantial differences in historical pathways also played a crucial role.

Growing up in a new world: trait divergence between rural, urban, and invasive populations of an amphibian urban invader

“…The species has successfully established invasive populations in Mauritius, Réunion, and near Cape Town (Constantia, South Africa) (Measey et al 2017;Telford et al 2019;Measey et al 2020b). Recent genetic analyses have confirmed that all three invasive populations originated from a clade located in the area around the port city of Durban in eastern South Africa (Telford et al 2019).…”

“…The decoupling of traits might also be a potential driver for the apparent similarities in growth rates of guttural toad tadpoles. Furthermore, the guttural toad is an infamous urban exploiter with synanthropic behaviour, frequently making use of artificial light sources for foraging and artificial bodies of water for hydration and reproduction (du Preez et al 2004;Measey et al 2017;Vimercati et al 2017;Baxter-Gilbert et al 2020;Measey et al 2020b). Thus, the terrestrial stage of the species might benefit from ecological opportunities in urban environments that are not available for the aquatic stage and growth rate might be decoupled between the tadpole and adult stage.…”

Toad‐kill: Prey diversity and preference of invasive guttural toads (Sclerophrys gutturalis) in Mauritius

“…Guttural toads have a wide native distribution across large sections of east and southern Africa, excluding arid regions in Botswana, Namibia and western South Africa, and with invasive populations in Mauritius, Réunion and near Cape Town in South Africa (Measey et al., 2017; Measey et al., 2020; Telford et al., 2019; Figure 1). Recently, molecular studies have shown that all three invasive populations originated near the port city of Durban, within the species native range in South Africa (Telford et al., 2019).…”

“…The long‐standing persistence of guttural toads ( Sclerophrys gutturalis ) in Mauritius represents one such understudied invasive population with an identified need for ecological studies to be undertaken (Kumschick et al., 2017; Measey et al., 2020). Guttural toads were introduced to Mauritius as biocontrol agents for insect pests in 1922 and became invasive shortly thereafter (Cheke, 2010; Cheke & Hume, 2008; Owadally & Lambert, 1988).…”

“…The presence of guttural toads in Mauritius has been suggested to be a contributing factor leading to the declines and extinctions of several endemic native gastropods (Cheke, 2010; Cheke & Hume, 2008; Mauremootoo, 2003), as well as the decline of some carabid beetles (Motala et al., 2007; Vinson, 1935). Recent evaluations of the ecological impacts of invasive amphibians have identified that guttural toads pose a moderate impact to Mauritian invertebrates (within the Environmental Impact Classification for Alien Taxa (EICAT) framework; see Measey et al., 2016; Kumschick et al., 2017), although these assessments came with low confidence scores due to a lack of fundamental dietary data Measey et al., 2020).…”