Queensland northern quolls are not immune to cane toad toxin
Context: The release of the highly toxic South American cane toad (Bufo marinus) to the toad-free Australian continent in 1935, and their subsequent rapid spread over large areas of tropical Australia, has resulted in a massive decline of predators such as yellow-spotted goannas (Varanus panoptes) and northern quolls (Dasyurus hallucatus). In spite of dramatic declines of northern quoll populations in the Northern Territory, a few populations still persist in areas of Queensland where northern quolls have co-existed with toads for several decades.
Aims: To determine whether the remaining quoll populations in Queensland have evolved resistance to cane toad toxins.
Methods: The extracellular H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene was sequenced in four Queensland as well as four Northern Territory quolls. The transcribed sodium–potassium-ATPase enzyme from this gene is specifically targeted by toad toxins.
Key results: In all of the eight quolls, the sequences representing the 36 bp of the H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene were identical.
Conclusions: Our results showed that Queensland quolls have not evolved an increased resistance to the toad toxins. We therefore suggest that the persistence of northern quolls in a few toad infested areas of Queensland could to be due to a combination of optimal habitat quality, and concomitant large quoll numbers, as well as an aversion to feeding on these highly toxic amphibians.
Implications: We suggest that a sample of northern quolls from the Queensland populations should be captured and their response, as well as that of their offspring and grand-offspring, to cane toads should be investigated to guide management of this declining species.