Researchers have found a species of gecko that may represent the evolutionary origin of adhesion in lizards. A dwarf gecko species has very basic adhesive properties and is the only gecko in that genus with the ability to scale smooth surfaces. The details are in a study that was just published in the Biological Journal of the Linnean Society.
A research team from the University of California was investigating the evolutionary path of geckos’ frictional adhesion. Many geckos are able to climb up smooth surfaces and this ability has been studied extensively. In one genus, however, only a single species from South America is capable of this type of adhesion. In the Gonatodes genus, the only gecko that displays frictional adhesion is the tiny Gonatodes humeralis.
The team found that G. humeralis have setae, tiny microscopic hairs, on the bottom of their feet. They lack the fully functional foot pads found in other adhesive geckos but the setae allow them to stick to most smooth surfaces. This is possible due to van der Waals’ forces, an interaction that causes an attraction between the setae and smooth surfaces such as glass.
The researchers observed G. humeralis in its natural habitat and found that the setae gave them a huge advantage over other species in the genus. The geckos could quickly climb up leaves and stems while other members of the Gonatodes genus struggled or couldn’t climb the surfaces at all. This allowed G. humeralis to easily escape and avoid predators. While the evolution of setae was probably gradual, the trait drastically changed the ecological functions of the species.
The adhesive properties of geckos are of special interest to scientists in the biotechnology and nanotechnology sectors. Scientists have aimed to recreate the adhesive system for use in human technology. The team’s findings show that simplified versions, using just setae, could be effective. The researchers also gained new insight into gecko evolution.
Timothy E. Higham et al. On the origin of frictional adhesion in geckos: small morphological changes lead to a major biomechanical transition in the genus. Biological Journal of the Linnean Society (2016).