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

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.

Global realized niche divergence in the African clawed frog Xenopus laevis

“…In this case, the climate matching approach is well able to identify areas with high risk of further invasion but is less reliable in identifying actually unsuitable habitats. Further conservation measures need to prevent additional introductions in suitable habitats which may arise due to anthropogenic climate change (Ihlow et al., ), not only within the already invaded regions but also in those areas which are highlighted by our global hypervolume model.…”

“…A total of 925 occurrence records of X. laevis containing 826 records from the species’ native range in southern Africa, 38 records from Europe, 24 from North America, and 37 from South America were obtained from Ihlow et al. (). We follow the taxonomic interpretation by Furman et al.…”

“…As environmental layers, we obtained remotely sensed bioclimatic variables (Beaumont, Hughes, & Poulsen, 2005;Busby, 1991) with a spatial resolution of 3 arc min (Deblauwe et al, 2016), representing minima, maxima, and average values of monthly, quarterly, and annual ambient surface temperature as well as precipitation (Table 1) (Table 1). A total of 925 occurrence records of X. laevis containing 826 records from the species' native range in southern Africa, 38 records from Europe, 24 from North America, and 37 from South America were obtained from Ihlow et al (2016). We follow the taxonomic interpretation by Furman et al (2015) confining the native range of X. laevis sensu stricto to southern Africa (South Africa, Lesotho, Swaziland, Namibia, Zimbabwe, and parts of Botswana, Mozambique and Malawi).…”

Climate change and the future restructuring of Neotropical anuran biodiversity

“…We note this time period already encompasses recent climate change, but pre-climate change baseline data are lacking. These GCMs are frequently used in SDM studies, including in Neotropical areas (Tomillo et al 2015, Ihlow et al 2016. We used the RCP 4.5 as a conservative greenhouse emission scenario, the lower-emission scenario -RCP 2.6 -is unrealistic (requires negative emission, Van Vuuren et al 2011b).…”

Overland movement in African clawed frogs (Xenopus laevis): a systematic review

“…This has resulted in invasive populations on four continents (Measey et al, 2012) and the suggestion that climate-change may increase invasion success in Europe (Ihlow et al, 2016). Surprisingly, the ecology of X. laevis is better studied in invasive populations than in their native range, and this lack of ecological data from the native range is problematic as it stymies interpretation of invasive studies.…”