When scientific fiction replaces good science
Good science writers – as with all reporters – should verify the validity of their stories before publishing, making sure to cite the peer-reviewed research detailing a new discovery. But as in the case of the purported cane toad-eating frog, an exciting enough fact with weak empirical support can sometimes take off like….well, an invasive species.
In 2005 and 2006, several media sources (including the Australian Broadcasting Corporation, the BBC, and ESA’s journal Frontiers in Ecology and the Environment) reported that the native Australian Dahl’s frog could survive after eating cane toad metamorphs, which are normally toxic to predators. The report was exciting because the invasive cane toads have wreaked havoc on Australia’s ecosystems since their introduction in the 1930s, and this provided the first supposed evidence of a possible biocontrol to thwart the toads’ spread. The finding, however, was reported by a community watch organizer who had fed metamorphs to five Dahl’s frogs in a terrarium at his home.
As Rick Shine and colleagues point out in a Dec. 10 e-view paper in Frontiers, titled “The myth of the toad-eating frog,” this finding was based on anecdotal evidence and lacked an appropriate sample size, control groups and replicated groups. The finding was not reviewed by scientists; indeed, even when reported in the media, no other scientists were contacted to comment on the story. In a bizarre twist, Shine also reported in his paper that at least one prominent ecologist retold the story, believing it was supported by scientific evidence.
When Shine and his colleagues tested the frog in a controlled setting with replication, randomization and appropriate sample sizes, they found that Dahl’s frog is just as susceptible to cane toad toxin as other native species. More than half of frogs that ate the toad metamorphs in captivity died. Further, the frogs that tried to eat cane toad tadpoles spit them out and learned to avoid them in subsequent trials.
So, who’s responsible here? With today’s ease of self-publishing, the lines between expert and self-proclaimed pundit blur, making it ever more important for journalists to validate the reliability of their sources. But scientists are not guiltless – although this paper cries foul, it does so more than three years after the initial report. If good ecological science is to inform public policy decisions, it’s up to scientists to ensure that the facts reported are sound.