Life history variation in four populations of the Graphic Spiny Lizard, Sceloporus grammicus (Squamata: Phrynosomatidae), in central Mexico

Widely distributed lizard species that occur in contrasting habitats generally show distinctive morphological and thermal traits that are the results of local adaptations via sexual and natural selection. Here, we assessed the effect of sex and seasonality on morphology, thermal ecology, and perch height of Sceloporus grammicus of four populations in central Mexico. In all populations, males had larger body sizes, heads, and limbs than females. Females had larger abdominal vol-umes than males in two of the four populations. Females and males of the tree-boulder population were smaller than those of the cactus and grassland populations. Females of the tree-boulder population were also lighter in weight, with shorter forearms, than those of the cactus and grassland populations. Assessing thermal ecology, we found sex-specific differences in body temperature and behavioural thermoregulation in the grassland population, and seasonal variation in these ther-mal traits for lizards in the cactus, tree-boulder, and grassland populations. Lizards in habitats with closed canopy cover had lower body temperatures than lizards in more open habitats. Perch height did not vary between sexes or seasons in three of the four populations. We found that the intensity of fecundity advantage varies between female populations, and that thermal characteristics of lizards show specific relationships with perch height in each population, which is a signal of local adaptation of behavioural thermoregulation.