Latest news with #sex reversal
The Guardian
5 days ago
- Science
- The Guardian
‘Mind-blown': scientists discover sex reversal in kookaburras and lorikeets with cause unknown
About 5% of common Australian wild birds including kookaburras and lorikeets could have undergone a 'sex reversal' where their genetic sex does not match their reproductive organs, according to a new study. The study is thought to be the first to find widespread sex reversal across multiple wild bird species, but the cause of the phenomenon is not yet known. The results suggest sex reversal is more common in wild birds than previously thought, and have raised concerns about the potential impact of chemicals that can disrupt hormones in animals. Researchers tested 480 birds across five common species that had died after being admitted to wildlife hospitals in south-east Queensland. Researchers first used a DNA test to determine a bird's genetic sex; in birds, males have a pair of Z chromosomes and females have one Z and one W. But after dissecting the birds, they found a mismatch between the DNA test and the reproductive organs of 24 of the birds. Sign up: AU Breaking News email Associate Prof Dominique Potvin, a co-author of the research at the University of the Sunshine Coast, said the team were deeply sceptical when the results first came in. 'I was thinking, is this right?' she said. 'So we rechecked, and rechecked and rechecked. And then we were thinking, 'Oh my God'.' Potvin said she had revealed the results to ornithologist friends. 'They were mind-blown,' she said. Almost all of the 'sex discordant' birds were genetically female but had male reproductive organs, found the research, published in the Royal Society journal Biology Letters. In one case, a kookaburra that was genetically male had a stretched oviduct – the passageway for an egg – that suggested 'recent egg production', Potvin said. Two genetically female crested pigeons had both testicular and ovarian reproductive structures, the research found. Other birds tested were rainbow lorikeets, scaly-breasted lorikeets and Australian magpies. The lowest levels of sex reversal was 3%, found in Australian magpies, and the highest was 6.3% in crested pigeons. Dr Clancy Hall, the lead author of the research, also at the University of the Sunshine Coast, said sex-reversed birds could affect reproductive success that should raise concerns about the impact on threatened species. She said: 'This can lead to skewed sex ratios, reduced population sizes, altered mate preferences, and even population decline. 'The ability to unequivocally identify the sex and reproductive status of individuals is crucial across many fields of study.' The causes of the sex reversals were unclear, but one factor could be contact with chemicals in the environment. Sign up to Breaking News Australia Get the most important news as it breaks after newsletter promotion Sex reversal is known to occur in some molluscs, fish, amphibians and reptiles and can occur naturally or be influenced by chemicals that can affect an animal's hormones – known as endocrine disrupting chemicals (EDCs). Prof Kate Buchanan, who studies the evolutionary biology of wild birds at Deakin University but was not involved in the study, said because the default sex of birds was female, it was not surprising that most of the sex reversal affects were in the direction of female to male. She said: 'The most likely explanation of the masculinisation is some environmental stimulation, probably anthropogenic chemicals.' Buchanan has been part of research that has found EDCs in insects that develop in sewage treatment works and are food for some birds, as well as a study that found male European starlings exposed to the chemicals developed longer and more complex songs, but had a damaged immune system. She said even if the masculinisation of affected birds was reversible in their lifetime, 'it would probably knock them out of being reproductive'. Dr Clare Holleley is the head of vertebrate collections at the Australian government science agency the CSIRO and has studied sex reversal in lizards. 'What's doing this is now the big question,' she said. While a cause could be natural (for example, sex reversal in lizards can be triggered by temperature changes), Holleley said it was likely 'something else is going on'. 'If sex determination gets disrupted then something has to push you off track. The most likely [cause] is endocrine-disrupting chemicals.' Dr Golo Maurer, the director of conservation strategy at BirdLife Australia, said the research was likely to cause a stir in the ornithological field. He said the presence of EDCs and the potential impacts was a 'huge concern' given the other crises facing birds, from climate change to habitat clearance and plastic pollution. Some experts were cautious about extrapolating the results to the wider population of wild birds, because the birds were not a random sample but had been admitted to hospitals.
Yahoo
5 days ago
- Health
- Yahoo
Scientists discover sex reversal in Australian birds with cause unknown
A new study has found that about 5% of tested Australian birds have undergone a 'sex reversal'—meaning the birds' genetic sex did not match with their reproductive organs. 480 birds that had died after being admitted to wildlife hospitals in south-east Queensland were subjected to a DNA test and then a dissection. It was revealed that nearly all of the 24 birds that had undergone this surprising 'sex reversal' were genetically female, but had developed male reproductive organs. Although the cause of the phenomenon is still unknown, the discovery has left scientists worried about the potential impact that chemicals may be having on animals' hormones. Professor Kate Buchanan—who studies evolutionary bird biology but wasn't a part of the study—told The Guardian, 'The most likely explanation of the masculinisation is some environmental stimulation, probably anthropogenic chemicals.' Buchanan added that even if this masculinisation was reversible, 'it would probably knock them out of being reproductive.' Still, experts remain cautious of the findings since the birds were not a random sample, but had been tested after already being admitted to wildlife hospitals. Video transcript A new study has revealed that about 5% of tested Australian birds have undergone sex reversal, meaning the birds' genetic sex did not match their reproductive organs. Four hundred and eighty birds that had died after being admitted to wildlife hospitals in Southeast Queensland were subjected to a DNA test and then a dissection. It was revealed that nearly all of the 24 birds that had undergone this surprising sex reversal were genetically female but had developed male reproductive organs. Although the cause of the phenomenon is still unknown, the discovery has left scientists worried about the potential impact that chemicals may be having on animals' hormones. Professor Kate Buchanan, who studies evolutionary bird biology but wasn't a part of the study, told The Guardian the most likely explanation. of the masculinization is some environmental stimulation, probably anthropogenic chemicals. Buchanan added that even if this masculinization was reversible, it would probably still knock them out of being reproductive. Still, experts remain cautious of the findings since the birds were not a random sample, but had been tested after already being admitted to wildlife hospitals.
Yahoo
5 days ago
- Science
- Yahoo
Scientists find surprising sex reversal in Australian birds
Scientists have documented a surprising rate of sex reversal in wild Australian birds, a phenomenon that could be explained by rising pollution or other environmental triggers. A study of five common Australian species, including kookaburras, magpies and lorikeets, found around six percent of birds had the chromosomes of one sex but the reproductive organs of another. The findings indicated a surprisingly high number of birds had reversed their sex after birth, said researchers from the University of the Sunshine Coast. "This indicates that sex determination in wild birds is more fluid than we thought, and can persist into adulthood," said study co-author Dominique Potvin. The study performed DNA tests on almost 500 birds. The overwhelming majority of sex reversals involved genetically female birds growing male gonads. "We also discovered a genetically male kookaburra who was reproductively active with large follicles and a distended oviduct, indicating recent egg production," said Potvin. Sex reversal is well known in certain species of reptile and fish but is thought to be rare in wild birds and mammals. Scientists have documented how pollutants and even warm temperatures can trigger sex reversal in frogs. The cause of sex reversal in wild birds was not clear, the University of the Sunshine Coast study said. But it could be due to environmental factors, such as hormone-disrupting chemicals building up in wild areas. "Understanding how and why sex reversal occurs is vital for conservation and for improving the accuracy of bird research," added Potvin. The study was published this week in peer-reviewed journal Biology Letters. sft/tc
News.com.au
5 days ago
- Science
- News.com.au
Scientists find surprising sex reversal in Australian birds
Scientists have documented a surprising rate of sex reversal in wild Australian birds, a phenomenon that could be explained by rising pollution or other environmental triggers. A study of five common Australian species, including kookaburras, magpies and lorikeets, found around six percent of birds had the chromosomes of one sex but the reproductive organs of another. The findings indicated a surprisingly high number of birds had reversed their sex after birth, said researchers from the University of the Sunshine Coast. "This indicates that sex determination in wild birds is more fluid than we thought, and can persist into adulthood," said study co-author Dominique Potvin. The study performed DNA tests on almost 500 birds. The overwhelming majority of sex reversals involved genetically female birds growing male gonads. "We also discovered a genetically male kookaburra who was reproductively active with large follicles and a distended oviduct, indicating recent egg production," said Potvin. Sex reversal is well known in certain species of reptile and fish but is thought to be rare in wild birds and mammals. Scientists have documented how pollutants and even warm temperatures can trigger sex reversal in frogs. The cause of sex reversal in wild birds was not clear, the University of the Sunshine Coast study said. But it could be due to environmental factors, such as hormone-disrupting chemicals building up in wild areas. "Understanding how and why sex reversal occurs is vital for conservation and for improving the accuracy of bird research," added Potvin. The study was published this week in peer-reviewed journal Biology Letters. sft/tc
Yahoo
5 days ago
- Science
- Yahoo
Scientists find surprising sex reversal in Australian birds
Scientists have documented a surprising rate of sex reversal in wild Australian birds, a phenomenon that could be explained by rising pollution or other environmental triggers. A study of five common Australian species, including kookaburras, magpies and lorikeets, found around six percent of birds had the chromosomes of one sex but the reproductive organs of another. The findings indicated a surprisingly high number of birds had reversed their sex after birth, said researchers from the University of the Sunshine Coast. "This indicates that sex determination in wild birds is more fluid than we thought, and can persist into adulthood," said study co-author Dominique Potvin. The study performed DNA tests on almost 500 birds. The overwhelming majority of sex reversals involved genetically female birds growing male gonads. "We also discovered a genetically male kookaburra who was reproductively active with large follicles and a distended oviduct, indicating recent egg production," said Potvin. Sex reversal is well known in certain species of reptile and fish but is thought to be rare in wild birds and mammals. Scientists have documented how pollutants and even warm temperatures can trigger sex reversal in frogs. The cause of sex reversal in wild birds was not clear, the University of the Sunshine Coast study said. But it could be due to environmental factors, such as hormone-disrupting chemicals building up in wild areas. "Understanding how and why sex reversal occurs is vital for conservation and for improving the accuracy of bird research," added Potvin. The study was published this week in peer-reviewed journal Biology Letters. sft/tc
