For centuries humans believed that wall lizards lived together in three different colors, each with their own survival strategies.
For millions of years, scientists have observed that a single species of lizard has maintained a vibrant mix of colors, but now, much of that diversity has disappeared in a remarkably short period of time.
Strangely, researchers pointed to an unexpected cause: a bold green, highly aggressive and dominant wall lizard that has rapidly eliminated many color variations within its species.
Now, a powerful green version is taking over. These dominant “hulk” lizards are out-competing others, causing the yellow and orange forms to disappear.
It’s a dramatic reminder that evolution can flip the script faster than expected.
In many animal species, the different color types, known as color morphs, are more than just visual differences.
These variations often reflect different approaches to survival, such as how individuals compete for territory or attract mates.
Each color may represent a unique strategy that helps maintain balance within the population.
common wall lizard, or Podarcis MuralisWidely found in the Mediterranean Sea, it has long been an excellent example of this balance.
According to researchers, these individuals typically display one of three throat colors: white, yellow or orange.
For millions of years, these color morphs coexisted within the same population, maintaining a stable evolutionary system.
Analysis of over 10,000 individual lizards. The findings were clear. A group known informally as “Hulk” lizards have changed the dynamics within the species.
To understand what’s going on, researchers examined color patterns in about 240 populations.
These larger, more aggressive lizards, distinguished by their attractive appearance, have spread rapidly. The yellow and orange throated types are disappearing as they spread into new areas. At many places only white color remains.
“Aggressive behavior disrupts the nuanced social systems that previously enabled multiple color strategies to co-exist,” said researcher Tobias Uller, professor of evolutionary biology at Lund University.
This research highlights how even long-standing evolutionary systems can be fragile and how a dominant trait can reshape competition and alter the balance within a species in a short period of time.
The research, led by Lund University, was originally published in the journal Adaptive spread of a sexually selected syndrome eliminates an ancient color polymorphism in wall lizards..
