Study of more than 600 animal and plant species finds genetic diversity has declined globally

Genetic diversity in animals and plants has declined globally over the past three decades, an analysis of more than 600 species has found.

The research, published in the journal Nature, found declines in two-thirds of the populations studied, but noted that urgent conservation efforts could halt or even reverse genetic diversity losses.

Dozens of scientists internationally reviewed 882 studies that measured genetic diversity changes between 1985 and 2019 in 628 species of animals, plants, fungi and chromists (a type of organism), forming what they have called “the most comprehensive investigation” of changes in genetic diversity within species to date.

The study’s lead researcher, Assoc Prof Catherine Grueber of the University of Sydney, said within-species diversity – referring to the variation between individuals of the same species – enabled a population to better adapt to changes in its environment.

“If a new disease comes through, or there’s a heatwave, there may be some individuals in the population that have certain characteristics that enable them to tolerate those new conditions,” she said.

“Those characteristics will get passed on to the next generation, and the population will persist instead of going extinct.”

Maintaining genetic diversity in wild and domesticated species formed a key component of one of the goals adopted at the biodiversity conference Cop15 in 2022.

Many of the leading causes of genetic diversity loss were the same culprits as for declines in populations, Grueber said: “Things like habitat loss, climate change, invasive species, new diseases.”

The researchers found ecological disturbances in 65% of the populations they studied, including human harvesting or harassment and changes in land use. But they noted that genetic diversity loss occurred even when no disturbances were reported, suggesting a “background level of genetic diversity loss across species”.

“We think that this represents the more general biodiversity crisis that the planet is facing, and broader effects of ecological disruptions [such as] climate change,” Grueber said.

However, she highlighted several instances in which tailored conservation strategies have improved genetic diversity.

This included a project to establish new populations of golden bandicoots – a threatened species – in Western Australia. “By understanding where they were selecting the animals from … and monitoring those populations using genetic studies, they were able to show that they could maintain the genetic diversity of those populations through multiple generations,” Grueber said.

In the US, conservation biologists were able to preserve genetic variability in black-tailed prairie dogs by dusting them with insecticides, preventing fleas from spreading plague during an outbreak. “The populations were able to thrive, and by moving around more in the landscape, they were able to interbreed with other prairie dogs,” Grueber said.

In Scandinavia, arctic fox populations had declined due to the fur trade and now face stiff competition with red foxes for prey, but supplementary feeding and removal of red foxes has led to increases in genetic diversity there.

“It’s important that we preserve the genetic diversity of our natural systems,” Grueber said. “We have the methods to make it work.”

The meta-analysis included species from 141 countries, with more than 500 animal species included.

This article by Donna Lu was first published by The Guardian on 29 January 2025. Lead Image: Arctic fox populations declined in Scandinavia, but supplementary feeding and removal of red foxes has led to increases in genetic diversity.
Photograph: Lisi Niesner/Reuters.

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