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Ultra-sound uncovers lizard gender

20 May 2009

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Fourth-year radiography student Gina Westhorpe from the Department of Medical Imaging and Radiation Sciences has teamed up with the Royal Melbourne Zoo on a world-first study that uses ultrasound to determine the sex of juvenile and adult lizards.

As these reptiles take a number of months or years to reach sexual maturity, improved gender identification methods are needed to facilitate breeding across zoos and research facilities around the world.

The trial will determine whether ultrasound can be used successfully to determine the sex of several lizards including the sail-tailed water dragon, green iguana, frilled lizard and the Fijian crested iguana - all of which are poorly sexually differentiated as juveniles and/or adults.

Ms Westhorpe said the technique had not been tried before due to limited access to equipment and qualified operators.

Fourth year radiography students can choose to do coursework or a research project.

With an honours degree in zoology already under her belt, Gina was keen to undertake research that combined her skills, contacting the head veterinarian at Royal Melbourne Zoo, whom she knew shared an interest in the area.

"It is an ideal project," Gina said. "The identification of gender in lizards is critical to managing lizard populations.

"The zoo had a number of lizard species that could be investigated and Monash was able to provide the equipment and expertise."

The technique was trialled for the first time earlier this month.

"We found that ultrasound was fantastic for sexing adult lizards, however the juvenile lizards, being no bigger than your palm, are too small," Gina said.

"We are going to continue to scan the juvenile lizards once a month until we determine a benchmark age for scanning each species.

"I hope that we'll find that ultrasound provides an easy, non-invasive solution to determining gender during the juvenile period, and in doing so help zoos and facilities around the world to better plan their breeding programs."