Boyd’s Forest Dragon Changes Sex from Female to Male in Apparent World First

Boyd’s Forest Dragon Changes Sex from Female to Male in Apparent World First

Sea Life Aquarium Melbourne used to have a male and two female Boyd forest dragons. Shortly after the male died, the guards noticed some unusual changes in one of the females. After careful observation, they concluded that it was a sexual change, apparently never seen before in adult reptiles.

Boyd’s Forest Dragons are a small arboreal lizard that lives in the rain forest of northern Queensland. The dragon had changed sex before they had sex with the male and laid eggs which confirmed that it was female. However, now it has stopped egg production and has developed male physical characteristics including testes.

Keeper Tom Fair told IFLScience that the two women had been tough rivals for several years, although one was certainly influential. “The first thing that alerted us to the change was that the two of them started sitting on the same branch instead of going to the opposite end of the tank and shaking each other,” he said.

This can be the result of the death of the male or the transfer to a new circle at the same time. But then the guards observed that the dominant dragon began to grow again, before reaching the weight of ordinary women of about 100 grams (3.5 ounces). Moreover, its crest was thickening, an important observable difference between males and females of this species. The process took place slowly, but the unnamed dragon has now reached 160 grams (5.6 ounces), a typical male weight. “We performed an ultrasound to determine which reproductive organs were present,” Fair said in a statement.

“We thought it was the first for Boyd’s forest dragon,” Fair told IFLScience, “We didn’t expect it to be the first to learn for reptiles as a whole. First notes sexual changes have been observed in some bearded dragon eggs, but as far as he has learned, nothing has been recorded before in adult reptiles. Famously, the sexual change between amphibians was a plotting device to allow Jurassic Park to “find its way to life”. Fair knew the same thing was not common in reptiles, but it was a shock to discover it was unprecedented.

The aquarium does not have the resources to examine the dragon’s genetics to see if they have some extraordinary chromosomes or if it finds itself near a female without a male developing an appetite-like response. Fair told IFLScience that they are talking to scientists about conducting such experiments, but that ethical principles need to be considered, saying “this is not a research sample, an ambassador is an animal.” Similar concerns have prevented any other dragons from being added to the tank.

Meanwhile, the remaining females are getting eggs frequently and the group is keeping an eye on the mating behavior as well to see if there is any fertility besides the lucky branches sitting. Not yet observed.