Ord Lab
Behaviour and Evolution
UNSW | Sydney, Australia

Animal behaviour is arguably the most dynamic aspect of an animal's phenotype and presents a challenge to biologists wishing to study its evolution. Behaviour is often highly variable, even within the same individual, and difficult to quantify and study experimentally. Yet the way in which an animal interacts with its environment - how an animal 'behaves' - determines the sorts of selection pressures that an animal experiences. Animal behaviour therefore lies at the heart of many fundamental questions in evolutionary biology.

Communication is an integral component of many animal societies and is a common focus of research in the lab. There have been three recurring questions: 1) how does sexual selection (via male-male competition) influence the evolution of new and/or elaborate forms of communication; 2) to what extent does predation and habitat-dependent adaptation shape the way animals communicate; and 3) how much of the variation in communication observed across species reflects phylogenetic or historical effects?

How these questions relate to broad concepts in evolutionary biology are highlighted in some projects below.

Adaptations to major ecological transitions

Evolutionary lineages that undergo dramatic shifts in ecology are especially attractive for the study of novelity - new selective pressures can promote the evolution of new forms of behaviour.

Some of this sort of work is being done in Guam on fish. The majority of species in the family Blenniidae are aquatic, but there are a handful of genera that divide their time between the ocean and land, and still others that have made a complete transition to a terrestrial lifestyle. On land, these fish defend rock holes using headnods and flashes of a brightly coloured dorsal fin. Collectively, the group provides a series of evolutionary 'snapshots' of the invasion of land and the opportunity to study the innovations in behaviour that have resulted (e.g., headnodding).

Other work focuses on the unique gliding lizards of southern Asia (Draco spp).

Pacific leaping blenny lives exclusively on land; Guam
Phenotypic plasticity and macroevolution

Animal communication is often dependent on the environment - some signals are better suited for communication in certain habitats than others - and is often quite plastic. Communication therefore provides a wonderful model system in which environmentally-dependent plasticity can be quantifed in wild populations for a variety of closely related species. We can then examine whether plasticity buffers or accelerates evolutionary change when species invade new environments.

This work currently focuses on lizards. Caribbean anoles use headbobs and dewlap extensions to advertise territory ownership. The detection of displays, and how these lizards subsequently perform displays, is dependent on the level of visual 'noise' (caused by windblown vegetation) and ambient light at the time of display. By studying the extent displaying lizards vary in their ability to track changes in environmental conditions, we can explore how display plasticity might influence macroevolutionary divergence in communication. Some experiments use robotic lizards to 'playback' displays to examine the adaptive significance of changes in display.

A yellow-chinned anole responding to a robotic lizard; Puerto Rico
Genetic differentation and 'neutral' evolutionary change

Our understanding of how diversity originates in animal communication is heavily dependent on adaptive explanations. Yet the initial trigger of signal diversification need not be direct selection on signal design, but a by-product of genetic differentiation between populations. Using a population-level phylogenetic approach, we can examine whether: 1) signal divergence occurs between populations when animals communicate in different environments (divergence is adaptive); or 2) geographic variation in communication is explained by the degree populations are genetically distinct (divergence is 'neutral'). Playback experiments are then used to test whether, irrespective of its initial cause, divergences in communication facilitate reproductive isolation, with its obvious implications for speciation.

Eastern water dragons offer an ideal species to study these sorts of questions.

Eastern water dragon