The landmark study, published in the scientific journal Nature, used data spanning more than three decades (from 1985 to 2019). It examined 628 species of animals, plants, and fungi across all terrestrial and most maritime realms on Earth.
Two-thirds of the populations analysed are declining in genetic diversity. However, conservation efforts designed to improve environmental conditions, grow populations, and introduce new individuals for breeding—for example, habitat restoration and animal translocations—are sustaining and, in some cases, increasing genetic diversity in populations.
Genetics Unlocks Past Data
The team of scientists from countries worldwide, including four authors from Wageningen University & Research, used innovations in genetic analysis to gain new insights from decades-old studies. By creating a common measurement scale, they were able to make comparisons between studies, even when they used different methodologies and collected genetic data in different ways.
“This kind of comprehensive global study would not have been possible even 10 years ago,” said lead author Grueber from the University of Sidney. “Advances in genetics and statistics have given us new tools that mean we can continue to learn from studies long after they were carried out – a huge benefit when we are looking at populations and trends on a global scale.”
Boosting biodiversity with conservation
Conservation efforts that could improve or maintain genetic diversity include translocations – where animals are moved between populations to benefit a species or ecosystem – habitat restoration, population control – where some individuals are removed to improve conditions for those that remain – and controlling feral or pest species.
Successes include the reintroduction of the golden bandicoot into areas in Western Australia, the release of arctic foxes from captive breeding programmes in Scandinavia, translocation of greater prairie chickens into existing populations in North America, and the effective treatment of disease within black-tailed prairie dog populations, which has improved the health of colonies in north-central Montana in the US.
Strengthening Conservation Efforts
The authors hope the findings will encourage more conservation efforts and lead to increased protections for populations that are currently not managed. Philippine Vergeer, co-author from Wageningen University & Research: “The loss of genetic diversity, often referred to as 'silent extinction,' is called so because it is not immediately visible. This can create the illusion that nothing is wrong or that the issue is not yet significant. This research is exactly what we needed. It taught us to what extent genetic diversity loss occurs, in which species groups this mainly happens, and which management measures can help to mitigate this loss.”
Co-author Joukje Buiteveld adds: “Significant genetic diversity losses are occurring even in species that are not rare or endangered. This challenges the belief that this issue only affects small, at-risk populations. Proactive conservation strategies must be implemented to safeguard species in the long term before declines set in.”