Invasive amphibians in southern Africa : A review of invasion pathways

Invasive species cause large economic impacts, have complex environmental impacts (Pimentel 2011) and are now considered to be among the four major threats to biodiversity. This has been recognised by their inclusion in the Strategic Plan for Biodiversity of the Convention on Biological Diversity (Aichi Target 9; UNEP 2011). Combating invasions clearly requires a prioritisation approach, taking account of invasive species’ impacts as well as their pathways of dispersal (McGeoch et al. 2016). Impacts of introduced/invasive amphibians are significant (Kraus 2015; Measey et al. 2016) and include alterations to trophic networks (e.g. trophic cascades – Crossland & Shine 2010; Doody et al. 2009), novel and altered predator–prey dynamics (consumption of invertebrates – Beard 2007; Beard et al. 2003; vertebrates – Boland 2004), impacts on other amphibians’ breeding systems (acoustic competition – Both & Grant 2012), alteration of ecosystem processes (Beard, Vogt & Kulmatiski 2002; Sin, Beard & Pitt 2008) and changes in socio-economic indicators such as property prices (Kaiser & Burnett 2006). The distribution of amphibian introductions is not even, with the majority occurring in Europe, North America and Australasia (Kraus 2008).