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Relationships between hormones and aggressive behavior in green anole lizards: an analysis using structural equation
Eun-Jin Yang1, Walter Wilczynski
1Department of Psychology and Institute for Neuroscience, University of Texas at Austin 78712, USA.
Hormones and Behavior
|October 9, 2002
Summary
In Anolis carolinensis lizards, aggressive encounters increase aggressive behavior, which in turn boosts circulating androgens. This suggests an animal's own aggression drives androgen levels, not the other way around.
Area of Science:
- Behavioral Endocrinology
- Neuroethology
- Animal Behavior
Background:
- Aggressive behavior is often linked to circulating androgens.
- The directionality of the androgen-aggression relationship in social contexts is debated.
- Understanding this relationship is crucial for comprehending social behavior dynamics.
Purpose of the Study:
- To investigate the relationship between aggressive behavior and androgens in Anolis carolinensis lizards.
- To examine how social interaction affects the androgen-aggression relationship.
- To determine the causal pathway between social challenge, aggression, and androgen levels.
Main Methods:
- Male Anolis carolinensis lizards were exposed to either aggressive conspecifics or neutral stimuli for five days.
- Plasma androgen levels and aggressive behaviors were monitored throughout the study.
- Structural equation modeling (SEM) was used to test three hypothesized models of interaction.
Main Results:
- The aggressive encounter group showed increased aggressive behavior and circulating testosterone (T) levels that mirrored each other during the encounter period.
- SEM analysis supported a model where social stimulus triggers aggressive behavior, which then increases androgen levels (Model 2).
- Following five days of aggressive encounters, lizards exhibited heightened aggression during a subsequent intruder test, but their androgen levels did not differ from controls, supporting self-driven androgen increases.
Conclusions:
- Aggressive behavior, rather than social stimulus alone, appears to be the primary driver of increased androgen levels in this species.
- The findings suggest a feedback loop where an animal's own aggressive actions can elevate its circulating androgens.
- This research clarifies the complex interplay between social behavior and hormonal regulation in vertebrates.
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