Meeting Abstract

23.1  Tuesday, Jan. 4  Reproductive Morphology and Behavior in Anolis Lizards: A Comparative Analysis JOHNSON, Michele A.*; LOPEZ, M. Veronica; WHITTLE, Tara K.; WADE, Juli; Trinity University, San Antonio, TX; Trinity University, San Antonio, TX; Trinity University, San Antonio, TX; Michigan State University, East Lansing, MI michele.johnson@trinity.edu

Across vertebrate taxa, the size of morphological structures is generally associated with the frequency of their use. This relationship is particularly well documented for morphological traits that underlie both the courtship and copulatory components of reproduction. However, few studies have examined these structure-function associations in an evolutionary context. Here, we examined nine species of Anolis lizards to determine whether structures critical for courtship displays and copulation are associated with the evolution of the frequency of these behaviors in the field. Using 10 lizards per sex for each species, we sectioned samples of the muscles and cartilage that support extension of the dewlap, a sexually-dimorphic structure used primarily by males in courtship and aggression. We also sectioned hemipenes (male copulatory organs) and related muscles, testes, and kidneys in males. Measures of these morphologies showed consistent differences between the sexes, with males exhibiting larger reproductive structures and more frequent courtship behaviors than females. Analyses using independent contrast data showed no evidence that the rate of dewlap extension evolved in association with the sizes of dewlap morphologies. Yet, a clear positive relationship exists between copulation rates and the fiber size of the muscle that controls hemipene eversion, although other copulatory morphologies showed no associations with copulatory behavior. Together, these results suggest that the relationship between muscle fiber size and frequency of muscle use has evolved differently for the two components of reproductive behavior in anoles.