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Modes of sex determination in reptiles have undergone rapid turnover throughout their evolution. Reptiles display contrasting strategies, from complete genetic control of sexual fate (genotypic sex determination - GSD) to environmentally determined sex (e.g. temperature-dependent sex determination - TSD).

Here I describe the first instance of reptile sex reversal in the wild, in the Australian bearded dragon (Pogona vitticeps), and use this phenomenon to experimentally induce a rapid transition from GSD to TSD in this species.

Controlled mating of normal males to sex-reversed females produced viable offspring whose phenotypic sex was determined by temperature alone (TSD). Functional sex reversal coupled with temperature sensitivity in sex determination renders the W chromosome redundant, creating the potential for its loss through stochastic drift in small demes.

This work provides unparalleled empirical insight into how new sex-determining modes can evolve rapidly in concert with altered climate regimes, and raises concern about the capacity of species to adapt to rapid anthropogenic environmental change.

Biography

Dr Clare Holleley joined the Australian National Wildlife Collection (CSIRO) in 2016, where she works as an evolutionary geneticist. She is a member of several large research consortia conducting ground-breaking genomic research (CSIRO's Environomics Future Science Platform, Oz Mammal Genomes initiative, Koala Genome Consortium) and is part of a team recently awarded a $1mill ARC Discovery Grant. Prior to her ANWC appointment, she gained her PhD at UNSW and completed extensive postdoctoral training (Macquarie University, National Cancer Institute USA, Institute for Applied Ecology at the University of Canberra).

Her highest impact work (and the focus of this talk) is pioneering research on the dynamic evolution of sex-determination mechanisms under climate change. Recently published on the cover of Nature, her work has attracted global attention and several academic awards (e.g. 2014 ACT Young Tall Poppy Award). She pairs excellence in research with a commitment to science communication, offering time as an ECR mentor, engaging popular media coverage and crowd-funding ventures.

Evolution, Ecology and Genetics Seminar Series