Sexual dimorphism of locomotor performance in Tropidurus torquatus (Squamata: Tropiduridae) lizards ? body shape, size and limb musculature explain variation between males and females

NORONHA,CAROLINA; CURY DE BARROS, FABIO; KOHLSDORF, TIANA; BRANDT, RENATA; TULLI, MJ

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016

0024-4066

Sexual dimorphism (SD) is the evolutionary outcome of selection acting differently on males and females. Several studies describe sexual differences in body size, although other morphological traits might be allometric between sexes and imply functional consequences. Here we test if morphological differences between sexes in size and shape in the lizard Tropidurus torquatus explain variation in performance of four locomotor traits. Our results show that males are larger than females and also exhibit longer limbs, longer muscles and larger muscle cross-sectional areas, while females have longer trunks and more sharped anterior claws; males outperform females in all locomotor performances measured. Sexual differences in sprinting and climbing is related with body size, and climbing performance is also explained by limb lengths, by differences in lengths and cross-sectional areas of specific muscles, and by interlimb distances. Between-sex differences in exertion are also related to sexual dimorphism, despite associations with sharper posterior claws that are independent of sex. Grasping performance, however, is associated with some muscle and morphological parameters that are not sexually dimorphic. Together our results suggest that morphology might be under sexual selection in T. torquatus, given that better locomotor performance likely favors male lizards in typical activities of this polygynic species, such as territory defense and female acquisition. Moreover, the longer trunks that characterize females may confer more space to accommodate eggs. On the other hand, territory defense by males probably increases their exposure to predators, resulting in a synergistic effect of sexual and natural selection in the evolution of SD in T. torquatus.