Changes in the aquatic macroinvertebrate communities throughout the expanding range of an invasive anuran

Invasive species are among the most significant threats to biodiversity. They have direct and indirect effects on the colonized environments including the alteration of food webs structure by predation. Thus, the diet of invasive animal populations, and its effects on trophic networks, is a crucial factor that must be considered in the context of global change. In this study, we focused on the invasive population of the African clawed frog, Xenopus laevis in France, and compared the composition of the aquatic macroinvertebrate communities in colonized ponds of the core and the edge of the population range, as well as in surrounding areas. While previous studies recorded a broad diet of invertebrate and a low selectivity of prey items, they failed to identify the prey categories the most strongly affected. Here, we report a significant decrease in the proportion of nektonic macroinvertebrates in ponds occupied by X. laevis. Interestingly, this effect is not significant when evaluating the density of each taxonomic category of nektonic invertebrate separately. This result, combined with the existing literature, suggests that X. laevis preferably consumes large nektonic items first when it arrives at a new site and subsequently focuses on smaller planktonic or benthic prey after the proportion of nekton has been reduced.