New study reveals link between local-scale species changes and global extinction risk

A new international study involving Maria Dornelas, researcher at MARE/ARNET and the Faculty of Sciences of the University of Lisbon, shows that a higher risk of extinction is associated with a greater local decline of species. The study, led by the School of Biology at the University of St Andrews (Scotland), has just been published in Nature Communications,

The research analysed one of the most comprehensive long‑term ecological databases in the world, BioTIME, developed at the University of St Andrews and widely used to study biodiversity change. It examined more than 60,000 populations of 2,362 species, across 978 of marine and terrestrial assemblages, all monitored consistently for at least 20 years.

An assemblage refers to a group of species from the same taxonomic group that co-occur within the same geographic location and time period, such as, a bird or fish assemblage. Assemblage analysis allows researchers to systematically quantify changes over time and identify which species are thriving or declining, helping to understand the “winners and losers” in a context of accelerating global change.

The team compared the temporal prevalence trends of each population with its extinction risk status from the IUCN Red List. Despite complex relationships between the two factors, a clear pattern emerged: declining trends are associated with higher extinction risk. Across the dataset, fewer than 10% of populations showed clearly increasing or decreasing trends.

According to Maria Dornelas, “Given that the task of assessing biodiversity change is enormous and it is not possible to collect retrospective data from the past, we aim to maximise the use of all available information. These two large biodiversity databases have only limited overlap, and this study shows how they can be used together to deepen our understanding of biodiversity change.”

This is the first time researchers have assessed whether there is a consistent signal between population temporal trends and species extinction risk using community‑monitoring data rather than species‑specific assessments. The results reveal a clear association: when a species becomes increasingly less present in monitored communities year after year, its extinction risk tends to rise.

Text: Vera Sequeira and Zara Teixeira