Impacts of Climate Change on the Global Invasion Potential of the African Clawed Frog Xenopus laevis.

G. John Measey,Charlotte De Busschere,Rui Rebelo,Julien Courant,Flora Ihlow,Solveig Vogt,Dennis Rödder,F. André De Villiers,Anthony Herrel,Jean Secondi,Thierry Backeljau,Francesco Lillo

doi:10.1371/journal.pone.0154869

Abstract

By altering or eliminating delicate ecological relationships, non-indigenous species are considered a major threat to biodiversity, as well as a driver of environmental change. Global climate change affects ecosystems and ecological communities, leading to changes in the phenology, geographic ranges, or population abundance of several species. Thus, predicting the impacts of global climate change on the current and future distribution of invasive species is an important subject in macroecological studies. The African clawed frog (Xenopus laevis), native to South Africa, possesses a strong invasion potential and populations have become established in numerous countries across four continents. The global invasion potential of X. laevis was assessed using correlative species distribution models (SDMs). SDMs were computed based on a comprehensive set of occurrence records covering South Africa, North America, South America and Europe and a set of nine environmental predictors. Models were built using both a maximum entropy model and an ensemble approach integrating eight algorithms. The future occurrence probabilities for X. laevis were subsequently computed using bioclimatic variables for 2070 following four different IPCC scenarios. Despite minor differences between the statistical approaches, both SDMs predict the future potential distribution of X. laevis, on a global scale, to decrease across all climate change scenarios. On a continental scale, both SDMs predict decreasing potential distributions in the species’ native range in South Africa, as well as in the invaded areas in North and South America, and in Australia where the species has not been introduced. In contrast, both SDMs predict the potential range size to expand in Europe. Our results suggest that all probability classes will be equally affected by climate change. New regional conditions may promote new invasions or the spread of established invasive populations, especially in France and Great Britain.

Highlights

Plenty of evidence exists for impacts of climate change on ecosystems and ecological communities [1,2,3,4,5,6,7,8] Climate change modifies climatic factors such as ambient temperatures, precipitation, and the frequency of extreme weather events, which profoundly affects species’ geographical distributions [9]
In order to assess the present and future invasion potential of Xenopus laevis on a global scale georeferenced occurrence records, covering the species’ native distributional range in South Africa, as well as all known invasive populations in Europe, were obtained from recent literature [50] and supplemented by 286 new records collected during own field research (J.C., J.S., R.R., J.M., F.L., A.dV.)
Comparisons between the results obtained by our Maxent analyses, the results presented by Measey et al [50] and the results obtained via biomod2 were performed by rescaling the probability output and subtracting the potential distribution grids from each other

Summary

Introduction

Plenty of evidence exists for impacts of climate change on ecosystems and ecological communities [1,2,3,4,5,6,7,8] Climate change modifies climatic factors such as ambient temperatures, precipitation, and the frequency of extreme weather events, which profoundly affects species’ geographical distributions [9]. Rising ambient temperatures might promote range expansions beyond the northern range limits or favour altitudinal range shifts, while increasing temperatures enhance winter survival [9]. Biological invasions are assumed to increase in the future in response to globalisation and climate change [18, 20,21,22,23]. Climate change is widely considered to exacerbate the impact of invasive species by making additional space suitable, enhancing survival and reproduction success, and by improving the competitive capacity of non-indigenous species [9, 24,25,26]

Methods

Results

Conclusion