Habitat use and morphology of Bosc’s Fringe-Toed Lizard, Acanthodactylus boskianus, in central Tunisia

Abstract

Within-species differences in morphology can influence many aspects of an organism’s ecology. We
investigated the morphology and habitat use of Bosc’s Fringe-Toed Lizard (Acanthodactylus boskianus) in sub-desert
steppe habitat in central Tunisia. Our main objective was to verify the presence of sexual size dimorphism in our study
population and assess whether morphological differences between males and females corresponded to differences in
vegetation use while being pursued. We captured, measured, and then released 60 adults after conducting habitat assessment
trials, which consisted of pursuing an active lizard and recording the vegetation into which the lizard
escaped. Concurrently, we conducted vegetation transects throughout the study site to assess vegetation availability. We
recorded values for ten morphometric measures, all of which were larger for males than for females. For most measures,
males and females of the same SVL had comparable values. However, a positive interaction between SVL and sex was
evident, with males exhibiting increasingly larger hindlimbs and mass. Our investigation revealed selective habitat-use
patterns among A. boskianus that were independent of sex and body size. Lizards did not use plants based on their
availability, entering Aristida pungens (Three-awn Grass) and Retama raetam (White Broom) more but Rhanterium
suaveolens (Rhanterium) and Haloxylon schmittianum (Saxaul) less frequently than random expectations. For the three
most commonly used plants (Astragulus armatus (Milkvetch), Three-awn Grass, and White Broom), lizards chose to
enter larger plants. This use of habitat could stem from antipredator defense or thermoregulatory concerns. Our findings
differ from previous reports on the nature of sexual size dimorphism in A. boskianus and contribute to our understanding
of the complex interplay between morphology, behavior, and local environmental conditions in shaping the
ecology of A. boskianus.