Developmental origins of mosaic brain evolution: Morphometric analysis of the developing zebra finch brain
Article first published online: 5 MAR 2009
Copyright © 2009 Wiley-Liss, Inc.
Journal of Comparative Neurology
Volume 514, Issue 2, pages 203–213, 10 May 2009
How to Cite
Charvet, C. J. and Striedter, G. F. (2009), Developmental origins of mosaic brain evolution: Morphometric analysis of the developing zebra finch brain. J. Comp. Neurol., 514: 203–213. doi: 10.1002/cne.22005
- Issue published online: 9 MAR 2009
- Article first published online: 5 MAR 2009
- Manuscript Accepted: 15 JAN 2009
- Manuscript Revised: 8 DEC 2008
- Manuscript Received: 7 OCT 2008
- National Science Foundation. Grant Number: IOS-0744332
- German Academic Exchange Services. Grant Number: A-07-74197
- subventricular zone;
In adult zebra finches (Taeniopygia guttata), the telencephalon occupies 64% of the entire brain. This fraction is similar to what is seen in parrots, but many other birds possess a significantly smaller telencephalon. The aim of the present study was to determine the developmental time course and cellular basis of telencephalic enlargement in zebra finches, and then to compare these findings with what is known about telencephalic enlargement in other birds. To this end we estimated the volumes of all major brain regions from serial sections in embryonic and post-hatching zebra finches. We also labeled proliferating cells with antibodies against proliferating cell nuclear antigen and phosphorylated histone H3. An important finding to emerge from this work is that the telencephalon of zebra finches at hatching contains a thick proliferative subventricular zone (SVZ) that extends from the subpallium into the dorsal pallium. The data also show that the onset and offset of telencephalic neurogenesis are both delayed in zebra finches relative to quail (Galliformes). This delay in neurogenesis, in conjunction with the expanded SVZ, probably accounts for most of the telencephalic enlargement in passerines such as the zebra finch. In addition, passerines enlarged their telencephalon by decreasing the proportional size of their midbrain tectum. Because the presumptive tectum is proportionally smaller in zebra finches than quail before neurogenesis begins, this difference in tectum size cannot be due to evolutionary alterations in neurogenesis timing. Collectively these findings indicate that several different developmental mechanisms underlie the evolution of a large telencephalon in passerines. J. Comp. Neurol. 514:203–213, 2009. © 2009 Wiley-Liss, Inc.