Is there a field proxy for brain size in great-tailed grackles (Quiscalus mexicanus)?
- Published
- Accepted
- Subject Areas
- Animal Behavior, Neuroscience, Zoology
- Keywords
- field measures, endocranial volume, great-tailed grackle, brain size proxy, Quiscalus mexicanus, brain size, bird
- Copyright
- © 2015 Logan et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ PrePrints) and either DOI or URL of the article must be cited.
- Cite this article
- (2015) Is there a field proxy for brain size in great-tailed grackles (Quiscalus mexicanus)? PeerJ PrePrints 3:e791v1 https://doi.org/10.7287/peerj.preprints.791v1
Abstract
There is an increasing need to validate and collect data approximating brain size on individuals in the field to understand what evolutionary factors drive brain size variation within and across species. We investigated whether we could accurately estimate endocranial volume (a proxy for brain size) as measured by computerized tomography (CT) scans, using external skull measurements and/or by filling skulls with beads and pouring them out into a graduated cylinder for male and female great-tailed grackles. We found that while females had much stronger correlations than males, estimations of endocranial volume from external skull measurements or beads did not correlate with CT volumes at a standard that surpassed our strict criteria. We found no accuracy in the ability of external skull measures to predict CT volumes because prediction intervals from data points overlapped extensively. We conclude that we are unable to detect individual differences in endocranial volume using external skull measurements. These results emphasize the importance of validating and explicitly quantifying the predictive accuracy of brain size proxies for each species, and each sex, under consideration.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Supplemental Table S1: Skull data
Archive data for each Quiscalus mexicanus skull measured (SBMNH=Santa Barbara Museum of Natural History, MSB=Museum of Southwestern Biology, KU=University of Kansas Biodiversity Institute and Natural History Museum). *=Quiscalus mexicanus mexicanus