Biodiversity Long-Term Biodiversity Data Reveals Early Warning Signs of Extinction Risk

Long-term biodiversity data from the University of St Andrews is helping researchers detect early warning signs of extinction risk. By analysing more than 60,000 populations across marine and terrestrial ecosystems, the study shows that species with declining local prevalence are more likely to face higher extinction risk.

New research from the University of St Andrews has shown that higher extinction risk is associated with higher frequency of decreasing local prevalence of species, in an analysis of one of the most comprehensive long-term databases ever created, Biotime — a major tool to study biodiversity change also developed at the University of St Andrews.

Researchers from the School of Biology alongside a team of international partners, analysed over 60 000 populations of 2362 species across 978 marine and terrestrial assemblages. These populations have been sampled comprehensively over 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. Analysing assemblage-level data allows us to systematically quantify change over time for many species and populations, and identify which ones might be faring better, i.e. assessing the “winners and losers” amidst ongoing global change.

The analysis matched each population’s temporal prevalence trend with each species’ extinction risk from the International Union for Conservation of Nature (IUCN) Red List. The picture that emerged was of complex links between the two factors, but a clear signal also emerged that decreasing temporal trends were associated with higher extinction risk compared to the other trends. Overall, fewer than 10% of populations showed either increasing or decreasing prevalence over time

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Joint lead Author, Dr Faye Moyes from the School of Biology at the University of St Andrews, said: “Our results highlight the importance of assemblage level monitoring in conservation strategies and shows the value of long-term time series such as those in Biotime. “

Joint lead Author, Laura Antão, based at the University of Turku in Finland, added “We have assessed for the first time whether there is a consistent signal between population temporal trends and a species extinction risk status using assemblage monitoring data, rather than ‘dedicated’ species-level assessments. Finding a clear signal that decreasing prevalence is usually associated with a higher risk of extinction is a strong indication that we can detect impacts even for species that are not currently classified as at risk”.

As global environmental change continues to accelerate, extinction risks are rising and assemblages are being reorganised across taxa, biomes and realms. The team also revealed complex links between local temporal prevalence and extinction risk categories: some populations of threatened species could have stable or increasing trends, while non-threatened species could be decreasing. A better understanding of the processes that underpin such biodiversity changes is crucial for improving predictions and conservation strategies.

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Professor Anne Magurran, a senior author of the study, added: “These temporal trends could serve as early‑warning indicators and help target both new monitoring efforts and conservation actions. For instance, stable populations of at-risk species are of key conservation interest, while declining trends might highlight species that are missing from extinction risk assessments”.

Professor Maria Dornelas added: “Because the task of assessing biodiversity change is gigantic, and we cannot travel in time to collect more data in the past, we want to use all information available. These two large biodiversity databases have only limited overlap and this study shows us how we can leverage both to expand our understanding of biodiversity change.”

Original Article: Linking species local trends from assemblage monitoring to global extinction risk, Nature Communications, DOI:10.1038/s41467-026-74132-7

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