Biological invasions can profoundly alter natural communities through predation, competition, pathogen transmission and changes to food webs. The laboratory investigates these dynamics in aquatic and terrestrial ecosystems, with particular attention to interactions between native amphibians and reptiles and introduced species.
A major research focus is the American bullfrog, Lithobates catesbeianus (also referred to as Aquarana catesbeiana), which is considered one of the world’s most impactful invasive amphibians. Studies conducted in central Italy, together with analyses of the international literature, have shown that its effects on native communities change during development and also depend on the presence of other invasive species.
Adult bullfrogs can prey on native amphibians, whereas juveniles may compete with them for food and habitat. The presence of the invasive red swamp crayfish, Procambarus clarkii, can modify these interactions: when crayfish are available as prey, bullfrogs tend to consume fewer native amphibians. This finding shows that removing a single invasive species may produce unexpected effects and that management actions need to consider the entire network of interactions.
Research activities also include the study of alien freshwater turtles in urban environments. A survey of 311 ponds, fountains and lakes in Rome recorded six non-native species, with higher occurrence in larger urban lakes, and highlighted the role of pet abandonment in their spread.
Studies co-authored by Leonardo Vignoli have shown that:
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