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600+ species show declining Genetic diversity, study warns Photograph: (iStock)
A global study has revealed a concerning decline in genetic diversity among mammals, birds, and marine species, raising concerns about the long-term survival of many animals. This decline threatens species' ability to adapt to environmental changes and could increase extinction risk.
Genetic decline threatens species' survival
Conducted by an international team, the study analysed genetic diversity trends over 34 years, from 1985 to 2019. It examined 628 species, including animals, plants, and fungi across land and marine ecosystems. The findings, published in Nature, involved researchers from Australia, the United Kingdom, Sweden, Poland, Spain, Greece, and China.
The results reveal a troubling picture: two-thirds of the studied populations are losing genetic diversity, making them more vulnerable to environmental threats. Despite this, less than half receive any conservation management.
The study focused on animals, which made up 84.7% of the examined species. Among them, vertebrates accounted for 59.2%, invertebrates 25.5%, plants 12.7%, and fungi 1.9%. A small percentage—0.6%—belonged to a category known as eukaryotic species.
A surprising finding of the study was that genetic decline is occurring regardless of a species’ conservation status. Many studied species are not classified as endangered. According to the International Union for Conservation of Nature (IUCN) Red List, 39.3% are “least concern,” and 6.1% are “near threatened.”
Additionally, 33.8 percent hadn’t been evaluated, and 1.8 percent were labeled as “data deficient,” meaning there wasn’t enough information to assess their status. However, despite these classifications, the study showed even species thought to be safe could be experiencing genetic decline, increasing their vulnerability to future threats.
Black-tailed prairie dogs face threats
A prime example is the black-tailed prairie dog, a species found in the United States. Although its population appears stable, certain groups have suffered massive declines due to disease outbreaks. The study also found that one-fifth of the analysed species were classified as threatened, with 7.3 percent listed as vulnerable, 6.7 percent as endangered, and 4.9 percent as critically endangered.
A small number—0.2 percent—had already gone extinct. The loss of genetic diversity was severe among birds and mammals, caused by habitat destruction, land-use changes, diseases, and human activities like over-harvesting. Natural disasters, such as wildfires, floods, and changes in river patterns, also contributed to genetic loss.
The study says human-induced factors like habitat destruction, unsustainable hunting, and invasive species are accelerating genetic erosion, causing organisms to lose genetic variation, limiting their adaptability to environmental changes. When populations shrink and become isolated, they face a higher risk of inbreeding, making them more vulnerable to diseases and extreme weather.
“Population decline and fragmentation due to anthropogenic factors, such as habitat degradation, unsustainable harvest, invasive species, and extreme climatic events, lead to genetic erosion—loss of genome-wide genetic diversity and adaptive potential,” the study stated.
Genetic diversity is crucial for survival
Catherine Grueber, the lead author and an associate professor at the University of Sydney, emphasised the importance of genetic diversity in conservation. “When we speak about biodiversity, it is mainly about the number of species and whether they are going extinct. But it’s also important to consider the variation within those species,” she said.
She explained that genetic diversity allows species to adapt to new environmental challenges, such as disease outbreaks or climate changes. “If a population faces a new disease or a heatwave, genetic diversity increases the likelihood that some individuals will survive, preventing extinction,” she noted.
The study highlights the difficulty in predicting how environmental changes will impact different species. Grueber stressed that it’s hard to determine how much genetic diversity a species needs to survive in the future. “It’s uncertain how environmental changes will impact a species, and we cannot predict how a population may respond,” she said.
Despite its widespread distribution, disease outbreaks have caused devastating losses in some of the black-tailed prairie dog's populations. This suggests conservation efforts shouldn’t focus solely on endangered species but also maintain genetic diversity in all species before a critical point.
Conservation efforts help restore diversity
Despite the alarming findings, the study offered hope by highlighting successful conservation efforts that helped species regain genetic diversity. Strategies like habitat restoration, controlled breeding, and translocations reversed genetic loss. For example, the golden bandicoot, a threatened Australian species, benefited from programs that established new populations in Western Australia.
Similarly, efforts to restore habitats and relocate populations to safer areas have increased genetic diversity in the greater prairie chicken, a North American bird species.
Other species have benefited from conservation actions. The Scandinavian Arctic fox has benefited from efforts to prevent inbreeding, while disease control programs have helped protect Hine’s emerald dragonfly and the dusky gopher frog. Captive breeding and gene flow initiatives have also maintained genetic diversity in threatened populations.
Robyn Shaw, the study’s co-first author from the University of Canberra, emphasised the importance of learning from conservation successes. “Despite successes, we can’t be complacent. Two-thirds of the populations analysed face threats, and less than half received conservation management,” she warned.
Shaw stressed the need for effective conservation strategies to protect species in the long term. “It’s vital that we learn from what is working to protect species long-term,” she said.
This study underscores the urgent need to rethink conservation strategies. While preventing species extinction remains a top priority, protecting genetic diversity is equally important. Efforts should focus on maintaining healthy, genetically diverse populations before they reach the brink of extinction.
The study urges governments, researchers, and conservationists worldwide to act before more species lose their ability to adapt and survive in a rapidly changing world.
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