Invasive toxic prey may imperil the survival of an iconic giant lizard, the Komodo dragon

Although invasive species constitute a major threat to global biodiversity, the introduction of toxic prey into naive predator faunas may become particularly destructive. An example of such an introduction was the deliberate release of the highly toxic cane toad (Bufo marinus) to the toad-free Australian continent in 1935. Naive large Australian varanid lizards have recently been shown to suffer a massive increase in mortality (> 95%) when attempting to feed on this toxic amphibian. The high susceptibility of Australian varanids to toad toxin is caused by minor mutations in the sodium-potassium-ATPase enzyme. In the present study we show that Komodo dragons (Varanus komodoensis) have similar mutations within this enzyme as observed in Australian varanids demonstrating that dragons are extremely susceptible to toad toxin. During the last decade the black-spined toad (Bufo melanostictus) has been able to invade areas close to the five toad-free islands constituting the habitat of Komodo dragons. An invasion of highly toxic black-spined toads into dragon habitats may therefore cause similar dramatic increase in dragon mortality as recorded in Australian varanids imperiling the long-term survival of this giant and iconic lizard.