The pineal complex, aggressive behavior and thermoregulation in curly-tailed lizards, Leiocephalus carinatus

Male Leiocephalus carinatus exhibited five types of aggressive displays, two of which were used to quantify aggression in paired encounters. After the dominant and subordinate lizard were identified, the area over parietal eye/pineal gland of the latter was shielded. This resulted in the subordinate lizard selecting higher body temperatures, exhibiting more assertive displays toward the dominant lizard, and increasing its frequency of use of a heat source that was the limited resource, as defined in the test arena. All of these responses required 4-6 days to be expressed and were reversed when the shield was removed. The results suggest that the responses are hormonally-controlled, and possibly represent an interaction between the pineal complex and discrete brain nuclei and/or the thyroid gland.