Common lizard microhabitat selection varies by sex, parity mode, and colouration

Abstract

Background: Animals select and interact with their environment in various ways, including to ensure their physiology is at its optimal capacity, access to prey is possible, and predators can be avoided. Often conflicting, the balance of choices made may vary depending on an individual's life-history and condition. The common lizard (Zootoca vivipara) has egg-laying and live-bearing lineages and displays a variety of dorsal patterns and colouration. How colouration and reproductive mode affect habitat selection decisions on the landscape is not known. In this study, we first tested if co-occurring male and female viviparous and oviparous common lizards differ in their microhabitat selection. Second, we tested if the dorsal colouration of an individual lizard matched its basking site choice within the microhabitat where it was encountered, which could be related to camouflage and crypsis.

Results: We found that site use differed from the habitat otherwise available, suggesting lizards actively choose the composition and structure of their microhabitat. Females were found in areas with more wood and less bare ground compared to males; we speculate that this may be for better camouflage and reducing predation risk during pregnancy, when females are less mobile. Microhabitat use also differed by parity mode: viviparous lizards were found in areas with more density of flowering plants, while oviparous lizards were found in areas that were wetter and had more moss. This may relate to differing habitat preferences of viviparous vs. oviparous for clutch lay sites. We found that an individual's dorsal colouration matched that of the substrate of its basking site. This could indicate that individuals may choose their basking site to optimise camouflage within microhabitat. Further, all individuals were found basking in areas close to cover, which we expect could be used to escape predation.

Conclusions: Our study suggests that common lizards may actively choose their microhabitat and basking site, balancing physiological requirements, escape response and camouflage as a tactic for predator avoidance. This varies for parity modes, sexes, and dorsal colourations, suggesting that individual optimisation strategies are influenced by inter-individual variation within populations as well as determined by evolutionary differences associated with life history.

Keywords: Basking; Crypsis; Dorsal colour; Environment; Microhabitat; Oviparous; Pattern; Squamate; Viviparous.

Fig. 1

Relative proportions of habitat types encountered overall in the area (‘study area’) and within the microhabitats chosen by (A) oviparous and viviparous and (B) male and female lizards. Habitat types that differed between parity modes (A) or sex (B) are marked by an asterisk. Examples of different habitats are shown in panels C - E), including typical basking sites for common lizards, such as C) a dried log among heather, D) a dried clump of grass next to water, and E) patches of dry grass in the meadow

Fig. 2

Proportion of habitat component and factors that performed best (as assessed by DIC) in explaining variance in each habitat component. Different colours in the kernel density plot represent factors that differed significantly in the best performing model. The habitat used by lizards differed in all its components from the study area available (‘Random’; grey colour). The combination of red and yellow coded colours indicated that either parity mode or sex was another significant factor. For example, in cases where parity mode was a significant factor, the second and third column (oviparous males and females; coded red) differed from the fourth and fifth column (viviparous males and females; coded yellow)

Fig. 3

Dorsal pattern differs between sex and is associated with dorsal colouration. A Three females with examples of a reticulated, intermediate and linear pattern (left to right). B Proportions of individuals of reticulated, intermediate, or linear dorsal patterning, shown for males and females separately. C Reticulated individuals tend to have an overall lower lightness score in dorsal colouration

Fig. 4

Positive relationship between common lizard dorsal colouration and the colour of its local habitat. The plots show lizard hue compared to the hue of (A) its habitat and (B) its basking site. Plot (C) illustrates the relationship between lizard lightness and the lightness of its surrounding basking site. Effect sizes are included as R² derived from linear models