The balance of trade in alien species between South Africa and the rest of Africa

Katelyn T Faulkner,Brett P Hurley,John R.U Wilson,Mark P Robertson,Mathieu Rouget

doi:10.4102/abc.v47i2.2157

Abstract

Background: Alien organisms are not only introduced from one biogeographical region to another but also spread within regions. As South Africa shares land borders with six countries, multiple opportunities exist for the transfer of alien species between South Africa and other African countries; however, the direction and importance of intra-regional spread is unclear. Objectives: The aim of this study was to gain a greater understanding of the introduction of alien species into Africa and the spread of species between South Africa and other African countries. Method: We developed scenarios that describe the routes by which alien species are introduced to and spread within Africa and present case studies for each. Using data from literature sources and databases, the relative importance of each scenario for alien birds and insect pests of eucalypts was determined, and the direction and importance of intra-regional spread was assessed. Results: Alien species from many taxonomic groups have, through various routes, been introduced to and spread within Africa. For birds and eucalypt insect pests, the number of species spreading in the region has recently increased, with South Africa being a major recipient of birds (14 species received and 5 donated) and a major donor of eucalypt insect pests (1 species received and 10 donated). For both groups, many introduced species have not yet spread in the region. Conclusion: The intra-regional spread of alien species in Africa represents an important and possibly increasing threat to biosecurity. To address this threat, we propose a framework that details how African countries could cooperate and develop a coordinated response to alien species introductions.

Highlights

The movement of goods and people around the world is facilitating the introduction of organisms to regions where they are not native
Many alien organisms are introduced directly from one biogeographical region to another (‘inter-regional introduction’), the spread of species within biogeographical regions contributes to biological invasions (‘intra-regional spread’) (Chiron, Shirley & Kark 2010; Hurley et al 2016; Jaksic et al 2002; Roques et al 2016 in this article, the biogeographical region of interest is continental Africa)
Birds and eucalypt insect pests have been introduced through various introduction routes (Tables 3-A1 and 4-A1), but different scenarios were common for the two groups

Summary

Introduction

The movement of goods and people around the world is facilitating the introduction of organisms to regions where they are not native. Organisms that are native to a biogeographical region might spread within the region, either naturally or with the aid of humans, to areas where they are not native (Chiron et al 2010). Six introduction route scenarios that describe how alien species might have been introduced to the region and spread between continental South Africa (SA) and elsewhere in continental Africa (AF) were developed and examples identified. In these scenarios, both natural dispersal and the human-aided movement of species within the continent were considered as intra-regional spread. As South Africa shares land borders with six countries, multiple opportunities exist for the transfer of alien species between South Africa and other African countries; the direction and importance of intra-regional spread is unclear

Objectives

Results

Discussion

Conclusion