Larval interactions with an invasive species (the Cane Toad Rhinella marina) affect life-history traits in an Australian anuran (the Marbled Frog Limnodynastes convexiusculus)

The viability of a metamorph anuran can be influenced by its body size and the time it has taken to complete larval development. In a laboratory experiment, we show that the presence of tadpoles of the invasive Cane Toad Rhinella marina causes tadpoles of a native frog (Marbled Frog Limnodynastes convexiusculus) to metamorphose later and at smaller sizes. These effects may render frog metamorphs more vulnerable to desiccation and predation, but render them less vulnerable to Cane Toads. Marbled Frogs prey upon other anurans, including the highly toxic Cane Toad metamorphs. Small, late-emerging metamorph frogs are unlikely to encounter metamorph toads small enough to ingest; and hence, are less likely to be fatally poisoned by consuming the toxic invader. Developing in the presence of larval Cane Toads thus increases the native taxon's ability to survive the presence of toads postmetamorphosis. Predicting the ecological impacts of an invasive species on native taxa with biphasic life histories (such as most anurans) thus requires information on interactions in both aquatic and terrestrial environments. The expression of phenotypic plasticity in one phase may influence fitness in a subsequent phase, in complex and non-intuitive ways.