RELATIVE CORTICAL VOLUMES OF MALE AND FEMALE NEONATAL AND ADULT NORTHERN PACIFIC RATTLESNAKES (CROTALUS O. OREGANUS)
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1
California Polytechnic State University, Biological Sciences, United States
In Northern Pacific Rattlesnakes, (Crotalus o. oreganus) males have larger home ranges than females. In other snakes and squamate reptiles with sexual dimorphism in home range sizes, there are differences in the volumes of the cortical regions of the brain that are associated with spatial memory (medial, dorsal, lateral cortex). This dimorphism could arise from a greater demand placed on males to navigate a larger territory. Alternatively, males may be born with larger cortical regions, which then contribute to the ability to navigate a larger range. We hypothesize that sex differences in home range size of adults are reflected in sex differences in the volume of brain regions relating to spatial ecology. Additionally, we hypothesize that sex differences in relative volumes of cortical regions develop in adulthood. To determine if this dimorphism exists in Adult Northern Pacific Rattlesnakes, we collected and sacrificed adult male and female snakes. Brains were removed, embedded in gelatin, frozen, and sectioned. The sections were mounted, Nissl-stained and the relative volumes of the cortical regions were measured from digital images. To determine whether differences in cortical region volumes develop prenatally, we collected gravid female snakes and kept them in the laboratory until neonates were born. Neonates were sacrificed and the relative volumes of cortical regions were measured as in the adults. Adult male snakes do not have larger cortical regions than females, nor do neonates. However, there is a trend for adult males to have larger medial cortex volumes than adult females. These results support the hypothesis that any sexual dimorphism related to differences in spatial navigation must occur during adulthood. Furthermore, our results demonstrate that there is considerable variability in cortical volumes in free-ranging animals and multiple factors likely contribute to plasticity of these regions.
Keywords:
Medial Cortex,
neuroplasticity,
reptile,
sexual dimorphism,
Spatial Ecology
Conference:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology, Ann Arbor, United States, 11 Jul - 13 Jul, 2011.
Presentation Type:
Poster
Topic:
Brain and behavior
Citation:
Hammel
LJ,
Frazier
JA,
Taylor
EN and
Strand
CR
(2011). RELATIVE CORTICAL VOLUMES OF MALE AND FEMALE NEONATAL AND ADULT NORTHERN PACIFIC RATTLESNAKES (CROTALUS O. OREGANUS).
Front. Endocrinol.
Conference Abstract:
ISAREN 2011: 7th International Symposium on Amphibian and Reptilian Endocrinology and Neurobiology.
doi: 10.3389/conf.fendo.2011.03.00014
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Received:
27 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Ms. Laura J Hammel, California Polytechnic State University, Biological Sciences, San Luis Obispo, CA, 93407-0401, United States, laura.hammel07@gmail.com
Dr. Christine R Strand, California Polytechnic State University, Biological Sciences, San Luis Obispo, CA, 93407-0401, United States, cstrand@calpoly.edu