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Figure 4.1 Cuban knight anole toe pad. Retrieved from: Anoles as Models for Dry Fibrillar Adhesion – Anole Annals.
1. Adhesive Toe Pads (Lamellae and Setae)
1. Adhesive Toe Pads (Lamellae and Setae)
Anoles have specialized toe pads made up of expanded scales called lamellae, which are covered in fine filaments known as setae. These features increase surface contact with substrates, generating electrostatic force, that enable the lizards to cling tightly to surfaces such as leaves and bark (Muñoz et al., 2023). Additionally, muscular control allows anoles to rapidly engage and disengage adhesion, facilitating quick movement.
Anoles have specialized toe pads made up of expanded scales called lamellae, which are covered in fine filaments known as setae. These features increase surface contact with substrates, generating electrostatic force, that enable the lizards to cling tightly to surfaces such as leaves and bark (Muñoz et al., 2023). Additionally, muscular control allows anoles to rapidly engage and disengage adhesion, facilitating quick movement.
✔️ This adaptation is critical for arboreal lifestyles, enabling access to elevated microhabitats and escape from ground predators. It likely facilitated the adaptive radiation of anoles into diverse niches (e.g., twig, trunk, and canopy specialists).
✔️ This adaptation is critical for arboreal lifestyles, enabling access to elevated microhabitats and escape from ground predators. It likely facilitated the adaptive radiation of anoles into diverse niches (e.g., twig, trunk, and canopy specialists).
2. Dewlaps and Display Behavior
2. Dewlaps and Display Behavior
Male anoles—and some females—possess extendable throat fans known as dewlaps, which display species-specific variation in color, size, and pattern. These dewlaps can be actively extended and retracted, often in combination with head-bobbing and push-up displays, to communicate during courtship, defend territories, and engage in other social interactions (Muñoz et al., 2023).
Male anoles—and some females—possess extendable throat fans known as dewlaps, which display species-specific variation in color, size, and pattern. These dewlaps can be actively extended and retracted, often in combination with head-bobbing and push-up displays, to communicate during courtship, defend territories, and engage in other social interactions (Muñoz et al., 2023).
✔️ Reduces interspecies mating by signalling species identity. Enhances reproductive success through sexual selection (e.g., larger dewlaps correlate with dominance).
✔️ Reduces interspecies mating by signalling species identity. Enhances reproductive success through sexual selection (e.g., larger dewlaps correlate with dominance).
Figure 4.2 Dewlaps of Anolis proboscis (A), A. gemmosus(B), A. aequatorialis (C), and A. fraseri (D). Retrieved from: https://www.researchgate.net/publication/269997314_Notes_on_the_Natural_History_of_the_Little-Known_Ecuadorian_Horned_Anole_Anolis_proboscis.
Figure 4.3 An anole basking in sunlight within a scrubland habitat to regulate its body temperature. As ectotherms, reptiles like anoles rely on external heat sources to maintain physiological function. Retrieved from: Lizard - Parthenogenesis, Reproduction, Adaptations | Britannica .
3. Thermoregulation Strategies
3. Thermoregulation Strategies
Anoles exhibit a range of thermoregulatory strategies, from active basking to regulate body temperature (thermoregulation) to passively allowing their body temperature to align with environmental conditions (thermoconformity). For example, highland species often use rocks to absorb and retain heat, while lowland species seek shade to prevent overheating. Even within the same geographic area, species inhabiting sunny, open environments tend to have greater heat tolerance compared to their relatives in cooler, shaded habitats (Gunderson et al., 2018).
Anoles exhibit a range of thermoregulatory strategies, from active basking to regulate body temperature (thermoregulation) to passively allowing their body temperature to align with environmental conditions (thermoconformity). For example, highland species often use rocks to absorb and retain heat, while lowland species seek shade to prevent overheating. Even within the same geographic area, species inhabiting sunny, open environments tend to have greater heat tolerance compared to their relatives in cooler, shaded habitats (Gunderson et al., 2018).
✔️ Enables survival across thermal gradients and explains slower evolution of heat tolerance.
✔️ Enables survival across thermal gradients and explains slower evolution of heat tolerance.
4. Rebreathing Adaptation in Semiaquatic Anoles
4. Rebreathing Adaptation in Semiaquatic Anoles
Some anole species have developed the remarkable ability to dive underwater and breathe by using a bubble of air that forms on their snout, functioning similarly to the rebreathing mechanism seen in some diving arthropods (Boccia et al., 2021). Their hydrophobic skin repels water and traps air, enabling them to reinhale the bubble and exchange oxygen while submerged. Interestingly, this underwater breathing adaptation has evolved independently in multiple anole lineages.
Some anole species have developed the remarkable ability to dive underwater and breathe by using a bubble of air that forms on their snout, functioning similarly to the rebreathing mechanism seen in some diving arthropods (Boccia et al., 2021). Their hydrophobic skin repels water and traps air, enabling them to reinhale the bubble and exchange oxygen while submerged. Interestingly, this underwater breathing adaptation has evolved independently in multiple anole lineages.
✔️ Helpful to escape from predators in aquatic habitats. Highlights the role of exaptation, which are pre-existing traits repurposed for new functions.
✔️ Helpful to escape from predators in aquatic habitats. Highlights the role of exaptation, which are pre-existing traits repurposed for new functions.
Figure 4.4 Adult water anole (Anolis aquaticus) from Coto Brus, Costa Rica, with an exhaled – and recycled – air bubble. Photo by Lindsey Swierk. Retrieved from: Underwater Breathing by a Tropical Lizard – Anole Annals.
Figure 4.5 A city-dwelling lizard grips a cinderblock wall. Photo by Kristin Winchell. Retrieved from: Living on Earth: City Lizards Adapt Fast to Urban Living .
5. Rapid Evolutionary Responses Changes
5. Rapid Evolutionary Responses Changes
Urban-dwelling anoles like Anolis cristatellus have evolved longer limbs and an increased number of lamellae on their toe pads, enhancing their ability to grip smooth, human-made surfaces such as walls and windows (Winchell et al., 2020). Similarly, invasive species like Anolis sagrei adjust their perch height and limb morphology in response to predator presence. These examples highlight how strong selective pressures in both natural and urban environments can drive rapid phenotypic changes.
Urban-dwelling anoles like Anolis cristatellus have evolved longer limbs and an increased number of lamellae on their toe pads, enhancing their ability to grip smooth, human-made surfaces such as walls and windows (Winchell et al., 2020). Similarly, invasive species like Anolis sagrei adjust their perch height and limb morphology in response to predator presence. These examples highlight how strong selective pressures in both natural and urban environments can drive rapid phenotypic changes.
✔️ Demonstrates adaptability to human-altered environments.
✔️ Demonstrates adaptability to human-altered environments.
6. Ecomorphology (Convergent Evolution)
6. Ecomorphology (Convergent Evolution)
Caribbean anoles evolved into distinct ecomorphs, which are groups with similar morphologies and behaviors adapted to specific microhabitats, like trunk-ground, twig, grass-bush. Anoles’ limb length, body size, and tail shape correlate with perch use (Muñoz et al., 2023). For example: Trunk-ground anoles have long legs for sprinting on broad surfaces, while twig anoles have short limbs for navigating narrow branches. Natural selection drives repeated convergence in similar habitats.
Caribbean anoles evolved into distinct ecomorphs, which are groups with similar morphologies and behaviors adapted to specific microhabitats, like trunk-ground, twig, grass-bush. Anoles’ limb length, body size, and tail shape correlate with perch use (Muñoz et al., 2023). For example: Trunk-ground anoles have long legs for sprinting on broad surfaces, while twig anoles have short limbs for navigating narrow branches. Natural selection drives repeated convergence in similar habitats.
✔️ Demonstrates predictable evolution under shared ecological pressures. Supports the concept of adaptive radiation (diversification from a common ancestor).
✔️ Demonstrates predictable evolution under shared ecological pressures. Supports the concept of adaptive radiation (diversification from a common ancestor).
Figure 4.6 Classical scheme of the Anolis ecomorphs. Retrieved from: http://dx.doi.org/10.1002/ece3.908.
Figure 4.7 West Indian Anolis lizards representing the six Caribbean ecomorphs (A-F) and the morphologically similar mainland Draconura-clade species (a-f). (A) Anolis cuvieri; (B) Anolis pulchellus; (C) Anolis distichus; (D) Anolis stratulus; (E) Anolis lineatopus; (F) Anolis occultus; (a) Anolis petersii; (b) Anolis auratus; (c) Anolis ortonii; (d) Anolis omiltemanus; (e) Anolis bicaorum; (f). Retreived from: http://dx.doi.org/10.1093/biolinnean/blab072.
References
References
Boccia, C. K., Swierk, L., Ayala-Varela, F. P., Boccia, J., Borges, I. L., Estupiñán, C. A., & Mahler, D. L. (2021). Repeated
evolution of underwater rebreathing in diving Anolis lizards. Current Biology, 31(13), 2947-2954.
https://doi.org/10.1016/j.cub.2021.04.040.
Gunderson, A. R., Mahler, D. L., & Leal, M. (2018). Thermal niche evolution across replicated Anolis lizard adaptive
radiations. Proceedings of the Royal Society B: Biological Sciences, 285(1877), 20172241.
http://dx.doi.org/10.1098/rspb.2017.2241.
Muñoz, M. M., Frishkoff, L. O., Pruett, J., & Mahler, D. L. (2023). Evolution of a model system: New insights from the study
of Anolis lizards. Annual Review of Ecology, Evolution, and Systematics, 54(1), 475-503.
https://doi.org/10.1146/annurev-ecolsys-110421-103306.
Winchell, K. M., Schliep, K. P., Mahler, D. L., & Revell, L. J. (2020). Phylogenetic signal and evolutionary correlates of urban
tolerance in a widespread neotropical lizard clade. Evolution, 74(7), 1274-1288.
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