Brain Structure and Volume Variation of Australian Agamid Lizards under Constrating Natural and Sexual Selection

1:15 pm 10 Sep 2014

Australian National University PhD student Daniel Hoops is accessing the University of Western Sydney (UWS) NIF node to investigate how sociality, sexual selection and natural selection act on brain structure using Australian agamid lizards. Daniel is supervised by Prof. Scott Keogh at the ANU and Prof. Martin Whiting at Macquarie University. Using the 11.7 T MRI located at UWS Campbelltown Campus, UWS Facility Fellow Tim Stait Gardner and UWS PhD student Yanurita Dwihapsari are scanning over 280 lizard brains with 100 μm isotropic voxel resolution.

Daniel, Tim, and Yanurita are also scanning 10 brains at 50 μm isotropic voxel resolution to create the first ever 3D lizard brain atlas. Jeremy Ullmann from the Centre for Advanced Imaging at the University of Queensland (UQ), using software written by UQ NIF Informatics Fellow Andrew Janke, has been able to create an average brain, which, once segmented, will form the Atlas. This project illustrates the strength of NIF, drawing on equipment and expertise across nodes.

Australian agamid lizards were chosen for this study because of their variation in natural and sexual selection and because they have been well characterised leaving ample ecological data to investigate for correlations with the MRI data. This is made relatively straight forward by the well resolved Australian agamid phylogeny, enabling phylogenetically controlled comparisons. There is a wealth of ecological data to analyse with the brain data. Fourteen species have been selected for investigation, chosen specifically for contrasts in their behaviour, ecology and mating strategies. The brains of ten males and ten females from each species (total 280 brains) will be compared and differences in overall brain size and a variety of lizard brain regions such as the cortex, limbic region and cerebellum.

Given the number of brains that need to be scanned for this proj ect a high throughput technique was developed at the UWS node of NIF in collaboration with PhD stu dent Ben Moroney. This technique enabled an average of four brains to be scanned per hour. So far well over two hundred brains have been scanned and the high reso lution scans for the atlas are com plete. The average volumes and surface based morphometries of the brains, telecephalons, and cor tical subregions of each species will be used for statistical analysis.

The imaging component of this proj ect is partially funded through NIF’s Subsidised Access Program. For more information about the project please contact Prof. Scott Keogh, scott.keogh@anu.edu.au, and Daniel Hoops, daniel.hoops@anu.edu.au. For access to the imaging facility, please contact Dr Tim Stait Gardner, t.stait gardner@uws.edu.au.
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