Bearded dragons might change their genders, but they don’t lose their beards

Quick notes:

  • Bearded dragons are lizards that are native to Australia
  • Bearded dragons change sex while they are in their eggs depending on the temperature of their environment
  • Researchers have discovered male bearded dragons that are acting, mating, and child-rearing like females

What is a bearded dragon?

Bearded dragons are scale-covered Australian reptiles. There are eight different species, but they’re all cold-blooded desert dwellers. Although all eight species are native only to Australia, they are such curious, interesting little animals that they have been bred successfully as pets all over the world.

Bearded DragonBearded Dragon

The beard isn’t just in the name: bearded dragons, male and female, use their beards to communicate with each other and demonstrate aggression. Their beards can change color and get bigger depending on the individual lizard’s emotions and needs.

How do bearded dragons change gender?

Not only is the bearded dragons’ gender switch pretty amazing, but it is also incredibly unique. Bearded dragons don’t experience gender dysphoria: gender-bending bearded dragons actually change genders when they are still in their eggs.

Reptile gender determination is a little bit unusual even without the unique gender switching of the bearded dragon. Instead of chromosome-based gender determination (like humans, for example), reptile sex is determined by a combination of chromosomes and temperature. That means that a fertilized egg might become male or female depending on the exterior temperature. Cool, right? But for bearded dragons, it gets even more complicated.

Researchers at the University of Canberra in Australia recently discovered that the chromosomes of some bearded dragons weren’t matching up with their physical sexes. Even though these little lizards’ chromosomes said they were male, the lizards themselves were presenting as female, and that’s not just based on observed clothing choices and societal gender roles. Although these animals are technically male, they are able to reproduce just like female lizards.

… the chromosomes said they were male, [but] the lizards themselves were presenting as female.

Not only do these male-to-female lizards reproduce just like females, but they might also have an advantage that chromosomal female lizards don’t. Scientists have observed these MTF lizards laying nearly two times as many eggs as typical females, and they seem to have even stronger maternal instincts, potentially inspiring the next generation of bearded lizards to be even better and stronger. Could this combination of male chromosomes and female traits be the next level in bearded dragon evolution?

Scientists are continuing to experiment with bearded dragon reproduction to determine the exact cause of this unusual switch, but they’re pretty confident that it is tied to temperature. The recent influx in mixed-gender bearded dragons could be the result of rising temperatures in the bearded dragon’s native Australia.

Are bearded dragons the only animals that switch gender?

The short answer? No. Although bearded dragons are the only animals to have their unique gender switch scientifically documented, there are plenty of other animals in the world that change their genders based on circumstance, temperature, or other factors.

Green sea turtles’ genders are also determined in part by the temperature of their eggs during incubation. Hot temperatures lead to females while cooler temperatures lead to males. Cardinals can also have a unique gender situation: a cardinal’s feather color changes based on their gender, with males featuring red feathers and females sporting brown-grey. Some cardinals, however, have some of each.

These combo cardinals haven’t been observed participating in traditional mating activities, but they also don’t seem to be social outcasts.

A deeper dive — Related reading from the 101:

Some of these animals are even stranger than the bearded lizard!

Gender switches seem to be making bearded dragons even better, but what are other people and animals doing to live their best lives?