(Press-News.org) A new study published in Science is challenging long-held assumptions about how we measure genetic risk in endangered species. Researchers analysed whole genomes from hundreds of koalas, finding that populations previously considered most at risk are now showing early signs of genetic regeneration.
Conservation biologists have long assumed that when a population crashes, known as a bottleneck, genetic diversity declines and extinction risk increases through inbreeding and the build-up of harmful mutations. This study provides world-first evidence that the story is more complex.
A large-scale sequencing effort began after the 2019-20 Black Summer bushfires on the east coast of Australia intensified concern for the species’ future.
“Following the 2019-20 mega fires, there was an urgent need to establish a long-term genomic resource for koalas” said Dr Luke Silver, postdoctoral researcher at the University of Sydney. “By sequencing 418 whole genomes, we created a critical baseline to understand how koala populations are evolving over time.”
Analysis of the genomes revealed that populations with higher genetic diversity, such as those in northern Australia, generally carried more harmful genetic mutations and showed declines in effective population size.
“Koalas are a really interesting case study. Populations across regions have been managed very differently, which means that their genetic signatures also significantly vary. This work uses those differences to highlight a wider lesson in conservation genomics,” said Dr Collin Ahrens, Principal Research Scientist at Cesar Australia.
“Surprisingly, it’s the populations that had passed through severe historical bottlenecks that are expanding, resulting in the accumulation of new mutations and greater genetic combinations. This growth, like we see in Victoria, comes with real genetic advantages: fewer harmful genetic mutations, increased adaptive capacity and early signs of genetic regeneration.”
Koalas present ongoing management challenges across Australia. Northern populations remain in serious decline, while southern populations are overabundant. Conservation managers are simultaneously managing populations in crisis and those that are overabundant. While translocation was widely used in the past, it is now considered high-risk, complex, and expensive.
Victorian koala populations have long been viewed as genetically compromised because most stem from a severe historical bottleneck. While they retain the genetic signature of that event, the new research shows that many are now recovering. Through recombination, the natural reshuffling of genetic variation, and the accumulation of new variants, harmful mutations are being reduced and adaptive potential is increasing.
“Our findings tell a story of genetic recovery in these populations, not collapse,” Dr Ahrens said. “It’s world-first evidence that conservation decisions can’t rely on static measures of genetic diversity. We need to understand the direction populations are evolving.”
Dr Andrew Weeks, Director of Cesar Australia, said the implications extend well beyond koalas.
“For decades, we’ve treated genetic diversity as a simple scorecard of extinction risk,” Dr Weeks said. “But evolution is dynamic. Understanding whether a population is expanding, stabilising or declining over time may be just as important as measuring how much diversity it holds today.”
Beyond koalas, many threatened species have experienced bottlenecks, habitat loss and rapid environmental change. The research suggests that judging extinction risk based solely on static genetic measures risks misclassifying both danger and recovery and highlights the importance of understanding processes unfolding across generations.
ENDS
Photos of koalas and research paper available at this link.
(Photo credits: Cesar Australia)
Available for comment
Dr Collin Ahrens, Cesar Australia
Dr Andrew Weeks, Cesar Australia
Dr Luke Silver, The University of Sydney
Media contacts
Dr Collin Ahrens, Cesar Australia
cahrens@cesaraustralia.com
+61 448 792 828
Dr Andrew Weeks, Cesar Australia
aweeks@cesaraustralia.com
+61 401 289165
Marcus Strom, Science Media Adviser, The University of Sydney
marcus.strom@sydney.edu.au
+61 474 269 459
Research
Ahrens, C. et al ‘Escaping the bottlenecks: the demographic path to genetic recovery in koalas (Phascolarctos cinereus)’ (Science 2026). DOI: 10.1126/science.adz1430
Declaration
The authors declare no competing interests. There were not external funding organisations.
END
Worcester Polytechnic Institute (WPI) researchers have used a form of artificial intelligence (AI) to analyze anatomical changes in the brain and predict Alzheimer’s disease with nearly 93% accuracy. Their research, published in the journal Neuroscience, also revealed that the anatomical changes, involving loss of brain volume, differ by age and sex.
“Early diagnosis of Alzheimer’s disease can be difficult because symptoms can be mistaken for normal aging,” says Benjamin Nephew, assistant research professor in the Department ...
Three new studies from Hospital for Special Surgery (HSS) highlight the use and advantages of osseointegration (OI) for individuals with an amputation, in some instances challenging prevailing beliefs about which patients would benefit. Osseointegration is a surgical procedure that enables a prosthetic limb to be attached directly to the bone of someone who has had an amputation, eliminating the need for a traditional socket prosthesis.
The studies, which looked at safety and outcomes in both femur-level (above-the-knee) and tibia-level (below-the-knee) OI, were presented at the 2026 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) in New Orleans this week.
“Osseointegration ...
The Buck Institute for Research on Aging today announced the launch of Healthspan Horizons, a new initiative designed to address one of the most urgent challenges in modern medicine: how to measure, understand, and extend healthspan—the years of life spent in good health.
People are living longer—but too many of those added years are spent managing chronic disease. In other words, healthspan—the years of life lived in good health—hasn’t kept pace. A growing body of evidence suggests that many aspects of ...
Researchers at the University of Ottawa Heart Institute, the University of Ottawa and McGill University have launched ARCHIMEDES (Advanced Research Collaboration for Health Integration, Medical Exploration, and Data Synthesis), a national platform designed to give Canadian health researchers secure access to diverse health data, enable responsible data sharing across institutions and health data types, and support the development of advanced analyses, including AI algorithms.
Health research in Canada is often slowed by fragmented data systems, lengthy approval processes to transfer data, and limited mechanisms for secure cross-institutional collaboration. As a result, valuable ...
The Brain Prize 2026 is awarded to Professors David Ginty (US) and Patrik Ernfors (Sweden) for their pioneering discoveries on how the nervous system detects and processes touch and pain. Their work has rewritten textbooks and opened new avenues for the development of targeted treatments for conditions such as chronic pain and hypersensitivity to touch.
Copenhagen, March 5, 2026
The somatosensory system provides us with the sense of our own body and its physical interactions with the world. Our sense ...
In left atrial appendage occlusion, traditional interventional techniques are confronted with challenges such as poor adaptability between metallic devices and the left atrial appendage, incomplete postoperative endocardialization, and long-term complications including device-related thrombosis and peri-device leaks.
Although liquid materials can adapt to the chamber geometry and avoid myocardial injury, traditional liquids are unable to withstand the impact of high-speed blood flow and disturbances from vigorous heartbeat within the left atrial appendage, making ...
Accumulation of the protein tau in the brain is one of the hallmarks of Alzheimer’s disease. In a paper publishing March 5 in the Cell Press journal Cell Press Blue, researchers report a previously unknown mechanism that appears to enable the build-up of tau. The study, which employed animal and cellular models as well as patient tissues, suggests a key role for tanycytes—specialized brain cells that regulate brain-body signaling.
“Our ...
Researchers have found that targeted delivery of messenger RNA (mRNA) can restore sperm production and fertility in genetically infertile male mice. The findings, published today in Stem Cell Reports, demonstrate that transient mRNA treatment restored sperm production and enabled the birth of healthy offspring.
Up to 10% of couples worldwide are affected by infertility, according to World Health Organization estimates, and male factors are the primary cause in about half of those cases. In many instances, ...
A study published today in Stem Cell Reports demonstrates that genetically engineered human pluripotent stem cells (hPSCs) can overcome immune rejection in mice with humanized immune systems, surviving for five months in a stringent transplantation model. The findings provide proof-of-principle for the development of a potential universal donor hPSC line designed to resist immune attack.
Led by Danny Chan, University of Hong Kong, China, and Andras Nagy, Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, Canada, the research team inserted eight immunosuppressive genes into a single hPSC line to render the cells resistant to immune rejection. When transplanted under ...
During the COVID-19 pandemic, mental health specialists started using telemedicine much more frequently. Despite many benefits, a new study finds that virtual visits did not make it easier for psychiatrists, psychologists and therapists to reach significantly more people in areas where access to care has long been limited.
By analyzing Medicare billing records from providers practicing across the country, researchers from the Brown University School of Public Health, Harvard Medical School and McLean Hospital showed that greater use of telemedicine among mental health specialists did not substantially change whether they were seeing ...
