Small hairs on the toes of the gecko species Gonatodes humeralis allow it to adhere to smooth, low-friction surfaces. Photo by Timothy Higham/UC Riverside
RIVERSIDE, Calif., Sept. 29 (UPI) -- Only 60 percent of geckos have adhesive toe pads. Of the 40 percent that do not, many belong to the genus Gonatodes, a group of dwarf geckos.
But new analysis suggests one Gonatodes species is on its way to developing adhesion. Researchers at the University of California, Riverside say Gonatodes humeralis offers a "snapshot" of evolution.
"The gecko adhesive apparatus, one of the most spectacular innovations displayed by vertebrates, has been intensively studied for the last 16 years and is of considerable interest to nanotechnologists and biomimeticists," Timothy Higham, a gecko expert and associate professor of biology at UCR, said in a news release. "But almost nothing is known about the origin of this adhesive capability."
While studying Gonatodes geckos, Higham and his research team were surprised to find microscopic hairs, called setae, beneath the toes of Gonatodes humeralis. The hairs produce attractive forces, called van der Waals forces, allowing the gecko to adhere to smooth surfaces.
In the forests of Trinidad and French Guiana, the hairy toes of Gonatodes humeralis allow it to adhere to leaves and bamboo shoots, safe from predators -- places its closest relatives are unable to venture.
Researchers say the species' adhesive toes -- all thanks to the sprouting of a few tiny hairs -- offer it a huge competitive advantage.
"Until now, we had not seen a gecko showing the beginnings of the adhesive system," Higham said. "In all the innovations seen in the animal kingdom, we rarely get to see their beginnings."
Higham says the new findings -- detailed in the Biological Journal of the Linnean Society -- offer further proof of the falsities of "intelligent design" theories.
"Complexity does not start with complexity. Small modifications can, however, lead to complexity," Higham said. "Key innovations can come about in small incremental steps and lead to feedback processes that result in the more complex renditions of such systems. Our research offers more experimental evidence to show this is true."