Meeting Abstract
Secondary sex characteristics differentiate males from females but are not directly involved in reproduction. The sexually dimorphic fence lizard, Sceloporus undulatus, has several secondary sex characteristics, such as color badges and body size, which appear in adulthood. In addition, post-anal scales – enlarged scales above where the hemipenes evert from the cloaca – distinguish males (who have these scales) from females (who do not) even at hatching. However, beyond being ubiquitously used as an easy, noninvasive way to sex many species of lizard immediately after hatching, little is known about this sexually-dimorphic trait. We tested for relationships between the size of post-anal scales and both testosterone levels and brightness of throat badge coloration in males from hatching to adulthood. We found that males with larger post-anal scales had higher testosterone levels and brighter throat badges. These results suggest that post-anal scales may function as a secondary sex trait in this and possibly other species. Further research should examine the mechanisms controlling the development and growth of post-anal scales, and their potential function (e.g. possibly in supporting the hemipenis during mating).
