Australian lizards feeling the heat
Researchers blame warming climate for apparent gender reversal in bearded dragons
WASHINGTON— Hotter temperatures are messing with the sex of Australia’s bearded dragon lizards, a new study finds.
Dragons that are genetically male hatch as females and give birth to other lizards. And the way the lizards’ sex is determined is getting changed so much that the female sex chromosome may eventually disappear entirely, say the authors of the study made in Australia.
“This is the first time we have proved that sex reversal happens in the wild in any reptile at all,” said Clare Holleley of the University of Canberra, lead author of the study in the journal Nature on Wednesday. The study, she said, “is showing that climate extremes can, very rapidly, fundamentally alter the biology of an organism.”
Holleley and colleagues examined the genetic sex markers of 131 wildcaught bearded dragons in Queensland state in northeastern Australia and found that 11 of them were female outwardly — even having offspring — but had the chromosomes of a genetic male. Their sex determination was “switched into overdrive,” Holleley said.
Holleley concedes 11 dragons is a small sample size, so she and colleagues will continue and expand their research.
The genetic-male-into-female dragons not only laid eggs, but in a way were better mothers than genetically determined females, laying more eggs, said study co-author Arthur Georges, chief scientist for the Institute for Applied Ecology at the University of Canberra.
The team also found that the offspring of these dragons no longer have their sex determined by chromosomes, but by temperature.
This is happening in an area that is one of the fastest warming places in Australia over the past 40 years, Holleley said.