Dorsal cortex volume in male side-blotched lizards, Uta stansburiana, is associated with different space use strategies

Spatial abilities have been associated with many ecologically relevant behaviours such as territoriality, mate choice, navigation and acquisition of food resources. Differential demands on spatial abilities in birds and mammals affect the hippocampus, the region of the brain responsible for spatial processing. In some bird and mammal species, higher demands on spatial abilities are associated with larger hippocampal volumes. The medial and dorsal cortices are the putative reptilian homologues of the mammalian hippocampus, yet few studies have examined the relationship between these brain areas and differential spatial use strategies in reptiles. Furthermore, many studies in birds and mammals compare hippocampal attributes between species that use space differently, potentially confounding species-specific effects with effects due to differential behaviours in spatial use. Here, we investigated the relationship between spatial use strategies and medial and dorsal cortical volumes in males of the side-blotched lizard. In this species, males occur in three different morphs, each morph using different spatial niches: large territory holders, small territory holders and nonterritory holders with home ranges smaller than the territories of small territory holders. We found that large territory holders had larger dorsal cortical volumes relative to the remainder of the telencephalon compared with nonterritorial males, and that small territory holders were intermediate. These results suggest that some aspect of holding a large territory may place demands on spatial abilities, which is reflected in a brain region thought partially responsible for spatial processing.