The Lizard LabBehaviour · Ecology · EvolutionMacquarie University, Sydney Australia

What we study

Our research

We are a behavioural ecology lab that works at both the ultimate (evolutionary) and proximate (genetic, physiological) levels of animal behaviour. We currently work on the evolution and maintenance of social behaviour, using mostly lizards as a model system. We are particularly interested in transitions between relatively simple social systems (e.g., mostly solitary living) and complex sociality (family living, living in societies)—how these may have evolved—and the mechanisms underpinning them. To this end, we use the Australian tiliquin skinks as a model system because they range in sociality from being solitary to living in nuclear families to complex societies consisting of a parental unit, multiple generations of offspring and including unrelated adults. We use a combination of field and lab-based approaches to our research. In particular, Martin has established a world-leading facility for studying lizards under semi-natural conditions. We also do lots of work on cognition (learning, memory, brain structure) in lizards, including trying to understand the selective forces driving brain evolution, including how brains are shaped by life history, predation, and social factors. Finally, we are interested in animal communication and the evolution of conspicuous signals via natural and sexual selection.

Framework linking lizard social systems, bonding mechanisms and social behaviour

Social evolution

Sociality and family living

We use the family-dwelling Australian tiliquin (Egernia–Liopholis clade) skinks to understand social plasticity and the origins of family living. We ask which social and environmental conditions drive species towards family living and cooperation, and the degree to which sociality is plastic.

Our work on mechanisms of complex sociality examines how the social environment interacts with the brain, how neuropeptides moderate aggression and enhance pair bonds and associations, and how maternal care affects offspring social development and cognition. Ultimately, we are interested in the possibility of a general theory for the evolution of vertebrate sociality.

Research figures illustrating animal communication and visual signals

Animal communication

Animal communication and sexual selection

We are interested in the design and information content of animal signals, particularly colour signals, and their role in fitness. We ask what a male’s colour signal conveys about quality to a female or competitive ability to a rival male, and also investigate chemical signals and their role in sexual selection.

We also study naturally selected colour signals such as flash signals in frogs and aposematic signals in arthropods. We are currently studying deimatic displays. These displays are almost completely unstudied in lizards. We have identified potential examples in independently evolved lizard clades in Africa, Asia and Australia with high ultraviolet reflectance, and investigate the factors driving their convergent evolution. We also take a comparative approach to the evolution of complex, dynamic tail waving in Asian toad-headed agamas and how these are related to brain structure.

Experimental designs used to investigate learning and cognition in lizardsBrain sections highlighting regions associated with social behaviour

Cognition

Cognition and brain evolution

Ultimately, with respect to learning, we are most interested in behavioural flexibility—an animal’s ability to adjust to changes in their environment (Cognitive Buffer Hypothesis) and solve novel problems or existing problems in a novel way. We have conducted a wide range of cognitive tests on lizards including tests of colour and shape discrimination (simple and compound stimuli), set shifting, spatial learning, inhibitory control, quantity discrimination, reversal learning, the decoy effect, precocial learning, and social learning.

We have also written reviews on lizard cognition, including methods for studying reptile cognition. We have studied learning in delicate skinks, water skinks, blue tongue skinks, gidgee skinks, sleepy lizards, bearded dragons, three-toed skinks, Mediterranean lacertids, tadpoles and frogs. We are also interested in how personality is related to cognition and how sociality and predation risk influence learning.

Seven-stage CRISPR-Cas9 workflow in lizards, from anaesthesia and surgery to edited offspring

Graphical abstract from Rasys et al. 2019. Cell Reports 28: 2288–2292.e3.

Genetics

Gene editing

Together with Oliver Griffith, we are doing CRISPR-Cas9 gene editing on lizards. Oli trained in Doug Menke’s lab as part of a Human Frontiers grant and has been leading our work in lizards. Yorick, Oli and Leo di Vita Morris have been mastering ultrasound to get the timing right for CRISPR surgeries. We are working on multiple species, but have had our best success with invasive tropical house geckos (Hemidactylus frenatus) in which we have knocked out the tyrosinase gene. Tyrosinase is responsible for pigmentation, so by knocking it out we have been able to produce albinos and thereby a proof of concept. Next steps will involve targeting different gene with specific questions in mind, related to sociality, climate change, sex, etc.

Collaboration

Global collaborative network

World map showing countries represented in The Lizard Lab collaborative network Explore the interactive network →

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