UC EVENTS

Sex determination in the dragon lizard is a complicated affair. They have sex chromosomes (a ZZ/ZW system of female heterogamety as in birds), but the chromosomal sex is over-ridded by high incubation temperatures -- ZZ individuals have their phenotype reversed to female. While such an environmental reprogramming of development is necessarily epigenetic, 50 years of research since temperature-dependent sex determination was first discovered (in a dragon lizard) have not provided much joy in uncovering the mechanisms. For a while, it was thought that temperature may cause a system-wide displacement of gene regulation leading to the production of one sex over the other, a so called parliamentary system. Recent work in our labs and those of others working on turtles have implicated ancient and highly conserved pathways cellular signalling and epigenetic processes of chromatin modification in capturing the environmental signal, and transducing it to effect the epigenetic release of key sex genes to determine sexual fate. This talk will summarize our progress to date on our grant nearing completion, and introduce what we plan to do to explore the epigentics of sex should we receive renewed funding.

Speaker Bio: 

Professor Arthur Georges is an expert on the evolution and ecology of reptile sex determination. The proposal that genetic and environmental sex determination represent ends of a continuum put by him and his colleagues at UC have shifted understanding of how the complex thermal environment of nests dictates sex in reptiles. Recent work by "Team Pogona" on sex reversal reveals molecular mechanisms of temperature sex determination and provides astonishing insight into the evolution of TSD and GSD, and how environment interacts with genotype to determine sexual fate. His work on the way the complex thermal environment within nests has redirected thinking on how reptiles survived past climate changes, and how human activities constrain their ability to respond to future challenges.