Initially, lizards had either a W chromosome that meant they would be genetic females or a Z chromosome, which made them males.
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As temperature, not genetics, begins to determine the sex of lizard offspring, researchers worry about all-female populations leading to species extinction.
The sex-reversed females also tended to lay about twice as many eggs as normal girl lizards, so over time, this resulted in a largely female population.
The cold-blooded Australian Central Bearded Dragon occupies open woodland and is conspicuous when it perches high to warm in the early morning sunlight.
The pilot excellent way the research Claire Hollely that are caused by the University of Canberra revealed that this can be the the first occassion that is actually researchers have noticed that sexual intercourse swap happens…
The researchers first studied the lizards in labs, then analyzed field data from 131 adult lizards and controlled breeding experiments, concluding through molecular analyses that some warmer lizards had male chromosomes but were actually female.
“Sex reversal occurs when the genetic sex of an individual, usually represented by sex chromosomes, is reversed to the other sex”, senior author Arthur Georges explained to Discovery News. If they only had a Z chromosome, that would make them a male member of the species.
In bearded dragons, sex is determined both by chromosomes and by the temperature at which eggs are incubated, the researchers report in their study published in the journal Nature. Genetically, these lizards are males but under hotter temperatures they hatch as females and give births to other lizards.
One of the authors of the study warned that if global warming continues, the amount of sex reversal could increase.
“It is often thought that once a species veers down the path of chromosomal sex determination, there’s no going back”, said Melissa Wilson-Sayres of Arizona State University.
She said sex reversal was widespread with instances distributed over a total area of nearly 15,000 square miles in remote semi-arid Australia.
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“One of the things we will be looking at into the future is whether they would be on an evolutionary dead end where they become more and more female and become extinct, or whether they can adapt and adjust their temperature threshold”, Dr Holleley said.
