Australian bearded dragon lizards can change gender in the egg – and hotter temperatures might be the reason, according to new research.
In a phenomenon known as sex reversal, the animal’s chromosomes, what they look like and how they act, do not match up. “So your genes are telling you that you should be a male, but you’re actually living out your life as a female,” Claire Hollely, from the University of Canberra, told ABC news.
She said the lizards that changed sex in this way could reproduce and were “completely functional” females. “The bearded dragons are the first species where we’ve actually been able to demonstrate this genetically. This is the first time … in a reptile, that we’ve actually found and established that sex reversal happens in the wild.”
The study of 131 adult lizards using controlled breeding experiments has been published in Nature.
The sex reversal took place during a period of “thermosensitivity in the middle of incubation”. If the egg is exposed to a hot temperature, this triggers the loss of the lizard’s sex chromosome (the equivalent of a male human losing the Y chromosome).
She said that the rate of sex reversal increased over the course of the study, which might be due to the rise in global temperatures, and required further study.
But for her the most interesting result was that the sex-reversed animals laid twice as many eggs as a regular female. “Basically dads make better mums,” she said.
Hollely said a type of skink was believed to experience the sex reversal phenomenon and that it also happened in fish.