Mural podarcis
Three variants of wall gecko have managed to coexist for millions of years. But the “Hulk” became very aggressive.
For millions of years, a common species of lizard maintained a rare balance in nature. Individuals with different colors coexisted in the same populations, each with its own survival strategy. Now, that balance is rapidly disappearing.
A new study in Science “points the finger” at a green, larger, more aggressive and dominant variant — and, precisely for this reason, nicknamed “Hulk”.
The species in question is the wall gecko (Mural podarcis), quite common in several regions of the Mediterranean. These animals usually have three types of coloring in the throat: white, yellow or orange. And these differences, highlights , are not just aesthetic. In many species, so-called chromatic forms are associated with distinct behaviors, including different ways of competing for territory, attracting mates or surviving in complex environments.
For a long time, these three variants managed to coexist, maintaining a stable evolutionary system. But that pattern is now being destroyed. According to researchers at Lund University in Sweden, the expansion of these “Hulk” lizards is profoundly changing the social dynamics of the species.
As these more aggressive individuals spread, yellow and orange variants are disappearing of many populations. In several places, only the white form remains.
To understand the size of the phenomenon, the team analyzed coloring patterns in around 240 populations and studied more than 10,000 lizards. The results show that the arrival and expansion of this dominant variant disrupted the social mechanisms that previously allowed the coexistence of several strategies within the same species.
Tobias Ullerprofessor of evolutionary biology at Lund University and one of the authors of the study, explains that researchers are observing the loss, in a very short evolutionary period, of a diversity that had been maintained for millions of years. For the scientist, These lizards’ aggressive behavior interferes with finely tuned social systemsessential for the maintenance of different chromatic forms.
The curious case shows us that evolution does not always advance slowly and gradually. When a new trait alters competition within a species, profound changes can occur, quickly.
