Sexual selection predicts brain structure in dragon lizards

Hoops, D., Ullmann, J. F. P., Janke, A. L., Vidal-Garcia, M., Stait-Gardner, T., Dwihapsari, Y., Merkling, T., Price, W. S., Endler, J. A., Whiting, M. J. and Keogh, J. S. (2017) Sexual selection predicts brain structure in dragon lizards. Journal of Evolutionary Biology, 30 2: 244-256. doi:10.1111/jeb.12984


Author Hoops, D.
Ullmann, J. F. P.
Janke, A. L.
Vidal-Garcia, M.
Stait-Gardner, T.
Dwihapsari, Y.
Merkling, T.
Price, W. S.
Endler, J. A.
Whiting, M. J.
Keogh, J. S.
Title Sexual selection predicts brain structure in dragon lizards
Journal name Journal of Evolutionary Biology   Check publisher's open access policy
ISSN 1420-9101
1010-061X
Publication date 2017-02-01
Year available 2016
Sub-type Article (original research)
DOI 10.1111/jeb.12984
Open Access Status Not yet assessed
Volume 30
Issue 2
Start page 244
End page 256
Total pages 13
Place of publication Chichester, West Sussex, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Subject 1105 Ecology, Evolution, Behavior and Systematics
Abstract Phenotypic traits such as ornaments and armaments are generally shaped by sexual selection, which often favours larger and more elaborate males compared to females. But can sexual selection also influence the brain? Previous studies in vertebrates report contradictory results with no consistent pattern between variation in brain structure and the strength of sexual selection. We hypothesize that sexual selection will act in a consistent way on two vertebrate brain regions that directly regulate sexual behaviour: the medial preoptic nucleus (MPON) and the ventromedial hypothalamic nucleus (VMN). The MPON regulates male reproductive behaviour whereas the VMN regulates female reproductive behaviour and is also involved in male aggression. To test our hypothesis, we used high-resolution magnetic resonance imaging combined with traditional histology of brains in 14 dragon lizard species of the genus Ctenophorus that vary in the strength of precopulatory sexual selection. Males belonging to species that experience greater sexual selection had a larger MPON and a smaller VMN. Conversely, females did not show any patterns of variation in these brain regions. As the volumes of both these regions also correlated with brain volume (BV) in our models, we tested whether they show the same pattern of evolution in response to changes in BV and found that the do. Therefore, we show that the primary brain nuclei underlying reproductive behaviour in vertebrates can evolve in a mosaic fashion, differently between males and females, likely in response to sexual selection, and that these same regions are simultaneously evolving in concert in relation to overall brain size.
Formatted abstract
Phenotypic traits such as ornaments and armaments are generally shaped by sexual selection, which often favours larger and more elaborate males compared to females. But can sexual selection also influence the brain? Previous studies in vertebrates report contradictory results with no consistent pattern between variation in brain structure and the strength of sexual selection. We hypothesize that sexual selection will act in a consistent way on two vertebrate brain regions that directly regulate sexual behaviour: the medial preoptic nucleus (MPON) and the ventromedial hypothalamic nucleus (VMN). The MPON regulates male reproductive behaviour whereas the VMN regulates female reproductive behaviour and is also involved in male aggression. To test our hypothesis, we used high-resolution magnetic resonance imaging combined with traditional histology of brains in 14 dragon lizard species of the genus Ctenophorus that vary in the strength of precopulatory sexual selection. Males belonging to species that experience greater sexual selection had a larger MPON and a smaller VMN. Conversely, females did not show any patterns of variation in these brain regions. As the volumes of both these regions also correlated with brain volume (BV) in our models, we tested whether they show the same pattern of evolution in response to changes in BV and found that the do. Therefore, we show that the primary brain nuclei underlying reproductive behaviour in vertebrates can evolve in a mosaic fashion, differently between males and females, likely in response to sexual selection, and that these same regions are simultaneously evolving in concert in relation to overall brain size.
Keyword Agamid
Lizard
Magnetic resonance imaging
Medial preoptic nucleus
Neuroscience
Reptile
Sexual dichromatism
Sexual dimorphism
Ventromedial hypothalamic nucleus
Visual modelling
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Centre for Advanced Imaging Publications
 
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