A study published in the journal Nature revealed that two-thirds of animal and plant populations are experiencing a decline in genetic diversity, making it increasingly difficult for them to adapt to environmental changes. Led by Catherine Grueber from the University of Sydney, the research analyzed data from 628 animal, plant, and fungal species across all continents and most marine regions. The team gathered knowledge from over 882 studies conducted between 1985 and 2019 to create a global overview of genetic diversity
"A surprising finding was that we saw genetic diversity decreasing even among many species that are not considered at risk," said Grueber, a conservation biologist and co-author of the study.
The research found that birds are the most affected by genetic diversity loss, followed by mammals, with two-thirds of the examined species impacted. This decline is often due to habitat restriction, natural events, diseases, and human activities such as hunting or logging. Terrestrial organisms are more affected than marine organisms, among which some species have even seen an increase in genetic diversity, according to Die Zeit.
Long before a species goes extinct, its population becomes smaller and more fragmented, which reduces genetic mixing. Reduced genetic mixing leaves a species more vulnerable to future threats such as disease. Higher genetic diversity increases a species' chance of survival. "When a species has different genetic solutions, it's better able to deal with changes," said David Nogués-Bravo at the University of Copenhagen, who was not involved in the study.
Conservation efforts to connect isolated populations—essentially expanding the dating pool for a particular species—can help maintain or even restore genetic diversity. This approach is crucial for allowing species to adapt to changing environments by providing a wider range of genetic traits. Among protective measures, legal protection was the most common at 23%, but the study showed it had little effect. The second most common measure is "supplementation," which involves adding individuals from one population to another or connecting separated natural areas so that members of different populations can meet.
In the study, supplementation was the only protective measure associated with a significant increase in genetic diversity compared to cases where no measures were reported. Examples include the reintroduction of Golden-shouldered Parrots in Western Australia, the release of Arctic Foxes from breeding programs in Scandinavia, and the relocation of Prairie Chickens into existing populations in North America. This approach also carries the risk of introducing diseases or maladapted genes or disturbing an existing healthy genetic population.
"It is undeniable that biodiversity is declining worldwide at an unprecedented rate," stated Grueber, but she also noted, "there are glimmers of hope" due to conservationists' actions. A large variation in genetic material among individuals is necessary for a species to adapt to its surroundings, especially during changes in the ecosystem such as those caused by climate change.
"Isolated populations suffer. The solution is to reconnect them," said Stuart Pimm, an ecologist at Duke University who did not participate in the research, as reported by Kenosha News. Conservation efforts that could improve genetic diversity include controlling invasive or harmful species, population control by removing certain individuals to improve conditions for those that remain, and introducing new individuals into certain populations for breeding.
The study found that existing conservation laws apparently do not provide sufficient protection against the loss of biodiversity. "Our analysis shows that there are already effective methods for conservation and data that make it possible to strategically target actions. By incorporating genetic considerations when conservation measures are planned and implemented, we can protect biological diversity and strengthen ecosystems' resilience to current and future challenges," said Grueber.
This article was written in collaboration with generative AI company Alchemiq