A study conducted at the University of Canberra suggests that Australian lizards may experience sex reversal due to global warming. Bearded dragon lizards have the ability to change their gender right in the egg. Sex reversal is a phenomenon when the animal’s chromosomes and their appearance do not match up physically.
According to the research published in the journal Nature the sex of reptiles does not depend only on chromosomes, but also on the surrounding temperature. It seems that when genetically male Australian bearded dragon lizards are exposed to extreme temperatures they turn into females.
The lead author of the study Claire Hollely from the University of Canberra said that this is the first time that scientists have observed that sex reversal occurs in the wild in reptiles. For the study the researchers used controlled breeding experiments to analyze 131 adult lizards.
Hollely explained that the animals reproduce and are functional females. If the animal had male sex chromosomes but reproduced as a female it produced twice as many eggs as normal females. Simply put fathers were better mothers.
According to Hollely the most intriguing part of the study is the fact that sex-reversed females produce more eggs than regular females. The offsprings of normal males and sex-reversed females were completely without sex chromosomes. This means that their sex is completely determined by the incubation period of the egg.
The climate changes caused by global warming affects the entire lizard population in such a way that the sex of the lizards may no longer be determined by the genetic signals of chromosomes, but by the temperature. In addition, according to the co-author of the study, Arthur Georges, species of animals whose sex is determined by temperature are becoming much more exposed to extinction due to the fact that in case they need to adapt they have few evolutionary options. Georges remarked:
“Once bearded dragons become temperature dependent, the risk is that if it keeps warming they’ll produce 100 percent females and they’ll be at risk of extinction, so this is a concerning finding.”
The results are even more worrying because sex reversal was found to be widespread. Researchers have found such species across almost 15.000 square miles in isolated semi-arid regions in Australia.
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