Ontogeny of sleeping behaviour in four solitary species of Anolis lizard.

Despite the nearly ubiquitous nature of sleep in the animal kingdom, behavioural research on sleep has focused on a few model organisms and widespread behaviours studied in artificial laboratory settings. In this study, we examine the ontogeny of sleeping perch selection in four closely related species of arboreal lizard in situ. The study species each occupy similar habitats and share 'solitary' ecology wherein potential lizard competitors are absent, thus providing four partially independent replicates with which to test hypotheses. We find that structural niche, analysed as perch height, varies by age and sex. Males sleep higher than females and adults sleep higher than juveniles in three of four species. Adults exhibit greater variability in sleep site selection. These patterns may reflect diurnal behaviour or indicate selective differences in sleeping perch variability across sex and ontogeny. [ABSTRACT FROM AUTHOR]