Credit: Michelle McAulay
In humans, it is our father who determines our sex - by passing on either the X or Y chromosome to produce a baby girl (XX sex chromosomes) or a baby boy (XY chromosomes). However, this is not uniform across all species, and Tariq Ezaz is at the cutting edge of sex determination in animals today.
Ezaz is a geneticist at the University of Canberra, and was heavily involved in uncovering sex determination in dragon lizards. "[Many] lizards … use both genes and egg incubation temperature to determine their offspring's sex," he said, adding that extreme temperature changes to the nest can also override any sex determination.
The central bearded dragon (Pogona vitticeps) and Alpine three lined skink (Bassiana duperrevi) are two examples that have both had their unhatched eggs' sex overridden in the lab using drastic temperature changes, according to Ezaz. "This means that high incubation temperature has overridden underlying genetic effect resides on the sex chromosomes," he said.
Ezaz completed his PhD at the University of Stirling in Scotland, studying sex determination in a commercial fish called Nile tilapia. "I developed sex-specific DNA markers in this species, which can be used to identify sex at early stages of development in several lines of captive populations [of fish]," he said. This facilitated fish farmers in selecting male fish for aquaculture, because they grow faster than female and can be sold to market much faster.
Ezaz's first post-doctorate degree involved studying the difference between salmon's fat metabolism with both a planet based diet and meat-based diet. His team's research led to the development of a plant-based food for the salmon fishery industry as a result.
Since Ezaz's move to Australia in 2003 he has worked mostly on reptile sex determination, as well as other vertebrates including birds, frogs and fish. His research could be instrumental in conserving biodiversity among reptiles. It can be used in establishing breeding programs for endangered reptiles. "Particularly, [in] those species where temperature can override genetic signal may be vulnerable to climate change through production of individuals with one sex," he said.
This month, Ezaz was awarded an Australian Research Council (ARC) Future Fellowship under a program designed to keep the brightest minds working in Australia. The A$714,000 fellowship will cover Ezaz’s salary and research costs over the next four years, allowing him to devote more time to research. Ezaz's next project is to identify the novel genes that determine sex in the central bearded dragon.
"It is a turning point in my career and will establish me as an independent researcher and will allow me to collaborate with other experts in the field and mentor younger researchers," he said.
