Scientific telephone: The cautionary tale of the global coverage of lichens.

Scientific history has many examples of profound statements that are later found to be unsubstantiated. The consequences of such misinformation can be dire. In the present article, we present a case where an unevidenced estimate of global lichen coverage proliferated through both scientific literature and popular media. We traced this estimate to a non-peer-reviewed publication from 1987. We found 76 academic articles (collectively cited 4125 times) and 13 other academic documents citing the statistic, citation chains without source attribution, and instances where the number or context was changed. We also found the statistic 37 times in popular media, which is especially concerning, given that these media communicate science to the broader public. We demonstrate how an unevidenced statement can spread, change through time, and ultimately be repeated without demand for evidence. We hope this case unplugs the telephone and provides a cautionary tale for researchers to ensure critical evaluation of citation and communication practices.