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A Smaller Habenula is Associated with Increasing Intensity of Sexual Selection.
Daniel Hoops1,2,3, Martin J Whiting4, J Scott Keogh1
1Division of Ecology and Evolution, Research School of Biology, The Australian National University, Acton, Australian Capital Territory, Australia.
Brain, Behavior and Evolution
|January 4, 2022
Summary
The habenula, a brain region modulating behavior, shows evolutionary changes in lizards. Sexual selection influences its size differently in males and females, impacting responses to stimuli.
Area of Science:
- Evolutionary neuroscience
- Comparative neuroanatomy
- Behavioral ecology
Background:
- The habenula is a conserved brain structure involved in behavioral modulation.
- It is the most prominent bilaterally asymmetric structure in the brain.
- Comparative evolutionary studies of the habenula are lacking.
Purpose of the Study:
- To investigate habenular subregion volumes in Australian agamid lizards (Ctenophorus).
- To explore the effects of sexual selection on habenular asymmetry.
- To contribute to understanding habenular evolution and function.
Main Methods:
- Examined medial and lateral habenular subregion volumes in both hemispheres.
- Analyzed data across a group of Australian agamid lizards (Ctenophorus).
- Correlated habenular volumes with the intensity of sexual selection.
Main Results:
- In males, asymmetrical selection reduced lateral habenula size with increased sexual selection, potentially enhancing aggression.
- In females, symmetrical selection reduced both medial and lateral habenula size with increased sexual selection.
- Findings suggest sexual selection influences habenular structure related to reproductive motivation and reward processing.
Conclusions:
- Sexual selection impacts habenular structure differently between sexes in Ctenophorus lizards.
- Further research is needed on habenular function in reptiles.
- The habenula warrants increased attention in evolutionary neuroscience.
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