A new study indicates that bearded dragon lizards can change their gender when they are in their egg. The phenomenon, also known sex reversal, means that the looks of the animal does not match with its chromosomes. The research published in the journal Nature was conducted by researchers from the University of Canberra and it was led by Claire Hollely.
Bearded dragon lizards live in Australia and are the first case which confirms that sex can be changed by climate change. If the egg is incubated at extreme temperatures and the embryo inside is a male from a genetic point of view it can instead develop into a female when the temperature is too hot.
So far sex changes caused by temperature were only produced in laboratories. This is the first case which confirms that this phenomenon is also possible in the wild.
When sex-reversed females reproduced with normal males their offspring completely lacked sex chromosomes. In this case the sex is determined by the temperature at which the egg is incubated. Other studies show that adult lizard populations from warmer regions have a number of individuals that were females even though they possessed male chromosomes. Holleley also said that the lizards have entirely lost a whole chromosome in only one generation.
Even though the sex of the offspring is determined both by genetics and by the incubation period now that the temperatures are increasing due to the global warming the species risks to reach the point in which the genetic signals of chromosome will be entirely replaced with sex determination by temperature. Holleley remarked:
“What we have found is that temperature does potentially affect the evolution of the species. If they are going to be exposed to higher temperatures more frequently, that is potentially going to affect their biology.”
If the sex of the offspring will be determined by temperature the species will be more likely to go extinct because it no longer has evolutionary options which enable it to adapt. Arthur Georges, the co-author of the study, explained that if bearded dragon lizards become dependent on temperature they risk to produce only female population as the temperatures increase and thus the species will be faced with extinction.
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