On average, 30 per cent of all species worldwide have been threatened with extinction or already become extinct over the last 500 years. This was the result of estimates by 3,331 experts working on biodiversity in 187 countries. This large and diverse group was asked in a survey, led by the University of Minnesota and with the participation of iDiv and the University of Leipzig, to provide assessments of the change in the species they study. The results are expected to reduce knowledge gaps in existing scientific assessments of global biodiversity and thus improve the knowledge base for policy decisions. The study was published in the journal Frontiers in Ecology and the Environment.