Examining the role of testosterone in mediating short-term aggressive responses to social stimuli in a lizard.

Hormones have been suggested as a key proximate mechanism that organize and maintain consistent individual differences in behavioural traits such as aggression. The steroid hormone testosterone in particular has an important activational role in mediating short-term aggressive responses to social and environmental stimuli within many vertebrate systems. We conducted two complementary experiments designed to investigate the activational relationship between testosterone and aggression in male Egernia whitii, a social lizard species.

Repeatable intra-individual variation in plasma testosterone concentration and its sex-specific link to aggression in a social lizard.

Individual hormone profiles can be important generators of phenotypic variation. Despite this, work on the consequences of hormone profiles has traditionally ignored the large inter-individual variation within natural populations. However, recent research has advocated the need to explicitly consider this variation and address its consequences for selection.