It's not all about size: sexual size dimorphism and caudal autotomy of Campbell's Alligator Lizard, Abronia campbelli Brodie & Savage, 1993

Sexual dimorphism and caudal autotomy are poorly documented in the lizard genus Abronia . We analyzed sexual size dimorphism and caudal autotomy in 54 adult Campbell’s Alligator Lizards ( Abronia campbelli ) from Jalapa, Guatemala. We measured snout–vent length (SVL), head width (HW), and body mass (BM) for 29 males and 25 females. While both sexes showed similar SVL and BM, the males had significantly broader heads than females relative to body size and body mass. In addition, caudal autotomy was similar between males and females. This monomorphism in body size, coupled with dimorphism in head width, suggests that sexual selection, likely driven by male–male combat or the need to grasp females during mating, acts strongly on male head morphology in this species.