VANHOOYDONCK, B*; HERREL, A; MEYERS, J; IRSCHICK, DJ; University of Antwerp, Belgium; University of Antwerp, Belgium; Northern Arizona University, Flagstaff; Tulane University, New Orleans: The evolution of dewlap size in Anolis carolinensis

Secondary sexual traits are believed to function as signals of a male�s quality (i.e. mating success and survival). By investigating how the size or shape of a sexual trait relates to ecologically relevant performance measures, we can directly test whether a secondary sexual trait does represent a reliable cue. Furthermore, by measuring performance we can test whether natural selection and sexual selection pose conflicting demands on the same design trait. Anolis lizards are characterized by the possession of an extensible throat fan, or dewlap. Extensive variation exists in dewlap size and color among and within species. Although, it has been suggested that dewlap design might be important during male-male interactions, courtship, species recognition and predator encounters, it has not been tested whether relative dewlap size is a good indicator of performance. Here, we examine variation in relative dewlap size in Anolis carolinensis lizards. Over 400 individuals were sampled from a single lowland swamp population. We took measurements of dewlap size and performance (i.e. jump distance, acceleration capacity, clinging ability and bite force) on all individuals. We then tested whether relative dewlap size is a good predictor of the different performance traits and whether the four performance traits are inter-correlated. Size-corrected dewlap size appears to predict size-corrected bite force, while size-corrected clinging ability appears to be negatively correlated with size-corrected bite force. These data suggest that dewlap size is an honest indicator of an animal�s fighting ability and that bite force and clinging ability trade-off within A. carolinensis.