A Surprising Variety in a Common Species
Just a short drive from Rome, Dr. Javier Ábalos spots a lizard with a striking mix of charcoal, green, yellow, and fluorescent blue basking on a wall. Hours later, farther along the road to Poggio di Roio, another lizard appears—smaller, brown, with dark stripes and a narrower head. Despite their dramatic differences, both are adult males of the common wall lizard (Podarcis muralis). “Who’d guess they’re the same species?” Ábalos remarks, underscoring the extraordinary variation that can exist within a single species. These differences reveal that biodiversity isn’t just about counting species—it includes the genetic, behavioral, and morphological diversity within them.
The Evolutionary Dance of Colour Morphs
In Italy, the common wall lizard displays three main colour morphs: white, yellow, and orange. These variations have persisted for millions of years, maintained by complex social and sexual interactions. Some males show pale, almost white undersides; others have yellow bellies, while a third group exhibits vivid orange or reddish hues. This intraspecies diversity offers populations a reservoir of traits that may help them survive and adapt to changing environments. Dr. Nathalie Feiner of the Max Planck Institute notes, “Without such variation, evolution would stall, and the capacity for adaptation would be lost.”
Conservation Challenges for Aeolian Wall Lizards
On the Aeolian Islands north of Sicily, a related population—the Aeolian wall lizard—shows similarly striking colour variations on different islets. But their survival is under threat from habitat loss, invasive black rats, and especially the introduction of Italian wall lizards (Podarcis siculus). These invaders outcompete the native lizards for food and shelter, often monopolizing territories and limiting breeding opportunities. Conservationists, including Dr. Leonardo Vignoli, are working to establish safe habitats to help Aeolian wall lizards persist. Protecting these populations and their genetic diversity is critical, not only for the lizards themselves but for understanding and preserving the full complexity of biodiversity.
