Little is known as to how physiological differences may affect behaviors associated with visual information gathering. Males and females brown-headed cowbirds (Molothrus ater) are exposed to different selection pressures. I tested the hypotheses that these different selection pressures require males to have a higher density of photoreceptors to detect the female's courting display, and that females require to expose their organs used to collect visual information to the object of interest with a more frequent succession to obtain quality visual information. Females had a significantly lower density of single and double cones than males. Females had significantly higher head-movement rates than males when visually exploring stationary objects. These results suggest that females have lower visual resolution than males, and compensate for that by moving their heads more quickly and exposing objects to different parts of the retina.
|Commitee:||Fernandez-Juricic, Esteban, Lowe, Christopher|
|School:||California State University, Long Beach|
|School Location:||United States -- California|
|Source:||MAI 52/01M(E), Masters Abstracts International|
|Keywords:||Molothrus ater, Photoreceptors, Sensory compensation, Sex differences|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be