Just twelve miles from Rome, a seemingly ordinary wall lizard reveals a surprising truth about the natural world: biodiversity isn’t just about how many species exist, but also about the incredible variation within them. Researchers are discovering that these differences, from vibrant colors to aggressive behaviors, are crucial for the survival of ecosystems.
The Spectrum Within a Species
The common wall lizard (Podarcis muralis ) displays striking diversity. One male might be charcoal-black with yellow speckles and blue spots, while another just miles away is brownish with dark stripes. Despite these differences, they are the same species, and their variation isn’t random. For millions of years, three distinct color morphs (white, yellow, and orange) have coexisted in Italy, maintained by complex social and sexual interactions.
However, a new study in Science reveals a potential disruption to this ancient equilibrium. A fourth, darker, more aggressive variation—known as nigriventris —is spreading, potentially driving the original morphs toward extinction. Researchers analyzed over 2,500 lizards across Italy and found that the nigriventris form, possibly originating from ancient islands in the region, is outcompeting its predecessors.
Why Intraspecies Diversity Matters
This isn’t just about aesthetics. Genetic, behavioral, and morphological variation within a species is essential for adaptation. Without it, evolution stalls, and a population’s ability to survive changing conditions is severely limited.
“Understanding and preventing the erosion of this diversity therefore lies at the very core of conservation biology.” – Dr. Nathalie Feiner, Max Planck Institute
Human activity poses a major threat to this diversity. The endangered Aeolian wall lizard (Podarcis raffonei ), found only on small islands north of Sicily, is being pushed toward collapse by habitat degradation, invasive rats, and competition with the Italian wall lizard (Podarcis siculus ).
Conservation Efforts: A Race Against Time
Researchers launched the Life Eolizard project in 2023 to prevent extinction and preserve the species’ unique diversity. The initiative combines habitat restoration, rat control, and removal of invasive lizards. Crucially, scientists have also begun captive breeding programs, selecting pairs based on genomic data to maximize genetic resilience.
“In 2025, we selected breeding pairs using genomic data and produced the first 64 captive-born juveniles of this species,” says Dr. Daniele Salvi of the University of L’Aquila. “This allows us to maximise genetic diversity and resilience so reintroductions start off strong in the wild.”
The project aims to reintroduce these captive-bred lizards into restored island ecosystems, creating safe havens for their long-term survival. The creation of sanctuaries on islands like Lisca Bianca and Bottaro is a turning point for the species, reshaping its distribution and improving its chances of recovery.
The story of the wall lizard highlights a fundamental truth: biodiversity isn’t just about counting species, but also about preserving the intricate variation that makes them resilient and adaptable. Protecting this hidden complexity is essential for ensuring the health of ecosystems and the future of life on Earth.
