Color Patterns in Mediterranean Wall Lizards

Jenn Hoskins
28th April, 2024

Color Patterns in Mediterranean Wall Lizards

Image Source: German Rojas (photographer)

Key Findings

  • Study in Mediterranean finds lizard color varies with island size and temperature
  • Lizards on smaller islands tend to be darker, possibly due to less predation risk
  • Color variations in lizards are not strictly inherited but influenced by the environment
In the Mediterranean, lizards of the genus Podarcis are a common sight, with their green-brown scales often blending seamlessly into their surroundings. Yet, some of these reptiles stand out with strikingly different colorations: vibrant blues and uniform blacks. Researchers at the University of Girona sought to understand the driving forces behind this chromatic diversity[1]. Their study examined whether these color variations were shaped by environmental factors, such as climate and habitat conditions, or by deeper, evolutionary influences. The study analyzed the coloration of 1,400 individuals across 27 species of Podarcis lizards. The researchers used a system called CIELAB color space, a precise method to quantify color that goes beyond what the human eye can discern, accounting for the way lizards would appear under natural lighting conditions in their habitats. The findings of this extensive survey revealed intriguing patterns. Color variations were not random but appeared to be influenced by both the environment and the lizards' evolutionary history. For instance, lizards from sunnier, rockier islands often exhibited lighter or more reflective coloration, possibly as a means of thermoregulation or camouflage. This aligns with previous research suggesting that the size and brightness of warning signals in aposematic wood tiger moth larvae can be constrained by temperature, affecting their growth and development rates[2]. Moreover, the study found that certain color traits were conserved across related species, indicating that some coloration patterns have been maintained throughout the lizards' evolutionary history. This phylogenetic trait conservatism suggests that once a particular coloration becomes fixed in a lineage, it may persist, potentially due to advantages it provides or through genetic constraints that limit change. The research from the University of Girona builds on earlier studies that have explored the balance between natural and sexual selection in shaping animal coloration. For example, research on Aegean wall lizards (Podarcis erhardii) found that sexual dimorphism in coloration, where males are more conspicuous than females, can increase males' risk of predation[3]. This trade-off between being attractive to mates and being visible to predators is a classic example of the complex forces that drive the evolution of animal coloration. Another dimension to consider is how coloration and behavior may evolve in response to predation pressure, as seen in the lizard species Podarcis gaigeae. Populations on islands with fewer predators were found to have bolder coloration and less fear of approaching observers, suggesting that predation pressure—or the lack thereof—can shape both physical attributes and behaviors[4]. The University of Girona's study not only provides a comprehensive analysis of color variation in Podarcis lizards but also contributes to our understanding of how different selective forces, including environmental conditions and predation pressure, can shape the evolution of animal coloration. By considering both current environmental factors and the historical constraints of these lizards' evolutionary past, the research offers a nuanced view of the interplay between an organism's phenotype and its ecological niche. In conclusion, the study sheds light on the complex evolutionary tapestry that gives rise to the diversity of lizard coloration in the Mediterranean. It highlights the importance of considering multiple factors, including climate, habitat, predator-prey dynamics, and historical lineage, in understanding the evolution of these remarkable reptiles. As researchers continue to unravel the intricate relationships between environment, evolution, and animal coloration, we gain a deeper appreciation for the subtleties of nature's palette and the myriad ways in which life adapts to survive and thrive on our planet.

EnvironmentEcologyEvolution

References

Main Study

1) Environmental colour pattern variation in Mediterranean Podarcis

Published 25th April, 2024

https://doi.org/10.1186/s12862-024-02242-1

Related Studies

2) Thermoregulation constrains effective warning signal expression.

https://doi.org/10.1111/j.1558-5646.2008.00561.x

3) Conspicuous male coloration impairs survival against avian predators in Aegean wall lizards, Podarcis erhardii.

https://doi.org/10.1002/ece3.1650

4) Does relaxed predation drive phenotypic divergence among insular populations?

https://doi.org/10.1111/jeb.12421


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