Biotic Interactions as Mediators of Biological Invasions: Insights from South Africa

Abstract

Ecological interactions, especially those that are beneficial (i.e. mutualism) or detrimental (i.e. parasitism), play important roles during the establishment and spread of alien species. This chapter explores the role of these interactions during biological invasions in South Africa, covering a wide range of taxonomic groups and interaction types. We first discuss the different ways in which interactions can be reassembled following the introduction of alien species, and how these depend on the eco-evolutionary experience of the alien species. We then discuss documented examples of parasitism and mutualism associated with invasions in South Africa and how these relate to various ecological and evolutionary hypotheses aimed at explaining species invasiveness. Selected examples of how invasive species impact on native species interactions are provided. A diverse array of biotic interactions (e.g. pollination, fish and mollusc parasitism, plant-soil mutualistic bacteria, seed dispersal) have been studied for various invasive species in South Africa. Surprisingly, only a few of these studies explicitly tested any of the major hypotheses that invoke biotic interactions and are commonly tested in invasion ecology. We argue that many invasions in South Africa are promising candidates for testing hypotheses related to species interactions and invasiveness.