A new study published in Nature warns that two-thirds of animal and plant populations are losing genetic diversity, making them more vulnerable to environmental changes and disease. Researchers examined data from 628 species between 1985 and 2019, finding the greatest losses in birds and mammals.

Before extinction, species often experience shrinking and fragmented populations, reducing genetic mixing and increasing susceptibility to threats. “A surprising trend was that genetic diversity declined even among species not considered at risk,” said Catherine Grueber, a conservation biologist at the University of Sydney.

Genetic diversity allows species to adapt to new challenges, such as climate shifts or disease outbreaks. “When a species has different genetic solutions, it’s better able to deal with changes,” explained David Nogués-Bravo from the University of Copenhagen.

Conservation efforts to reconnect isolated populations can help restore genetic diversity. A notable success is the Florida panther, which suffered from inbreeding due to habitat loss. In the 1990s, biologists introduced eight female panthers from Texas, leading to a significant population increase and improved genetic health.

“Isolated populations suffer,” said Duke University ecologist Stuart Pimm. “The solution is to reconnect them.”