Meeting Abstract
The dorsal and medial cortices (DC and MC) are hippocampal homologues in reptiles. These regions exhibit plasticity in response to changes in spatial navigation. For example, in side-blotched lizards, territorial males have larger DC volumes than non-territorial males. However, little is known about differences between males and females. In Sceloporus occidentalis, males have larger territory sizes than females. Given this, we expected males to have larger MC and/or DC volumes than females. However, previous work in our lab on captive lizards indicated that females have larger MC volumes than males. To determine if the sex differences we found in MC volume resulted from the conditions in our captive experiment or if they represent free-ranging animals, male and female S. occidentalis were captured from the wild during the breeding season and during the post-breeding season and were sacrificed within two days of capture. Brains were collected and processed for histology. Cresyl-violet stained sections were used to quantify brain region volumes. In these lizards, females had larger DC volumes than males but there was no sex difference in MC volumes. These sex differences may be related to differences in spatial navigation in these populations of lizards that may involve aspects of spatial memory other than territoriality. Future work will address behavioral differences in space use or territory size that may be related to these unexpected sex differences in cortical volumes.
