Toads have successfully expanded across the globe, with a recent surge in East Africa, as revealed by a study analyzing the DNA of 124 toad species. Scientists attribute the toads’ conquest to their toxic parotid glands, packed with lethal substances that deter predators.
The study, recently published in the Proceedings of the Royal Society B, suggests that the evolution of these glands empowered toads to thrive on new continents millions of years ago. Originating in South America around 61 million years back, toads later invaded Africa. The exact method of their transoceanic journey remains unclear, though hypotheses include using Antarctica as a land bridge or rafting on vegetation mats across the sea.
Notably, the introduction of toads to Madagascar via shipping containers mirrors the historical spread of cane toads in Australia. These invasive species pose a threat to native biodiversity, a concern shared by scientists observing the toads’ rapid proliferation.
In light of these findings, experts emphasize the critical role of human activities in inadvertently aiding the global dispersion of toads. This unintentional facilitation, akin to the historical introduction of cane toads in Australia, highlights the challenges faced in managing invasive species’ impact on ecosystems.