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Thu October 25, 2012
Dr. Tony Gamble, University of Minnesota – Evolution of Gecko Feet
In today’s Academic Minute, Dr. Tony Gamble of the University of Minnesota explains the mechanics of gecko feet and traces the evolutionary origins of the little lizard’s extraordinary climbing ability.
Tony Gamble is a postdoctoral researcher at the University of Minnesota where he is currently conducting research on the evolution of sex determining mechanisms in lizards. His previous work sought to understand the systematics and biogeography of geckos and used phylogenetic trees to study the evolution of complex traits, such as the gecko’s gripping ability. Learn more about Dr. Gamble's work by reading the full journal article.
Dr. Tony Gamble – Evolution of Gecko Feet
The climbing abilities of geckos have fascinated people for centuries. Geckos are a type of lizard and consist of over 1400 species, about 60% of which have adhesive or sticky toepads. Adhesive toepads allow geckos to run across smooth vertical or even inverted surfaces like ceilings with incredible speed. Recently scientists have discovered the molecular mechanisms that allow geckos to stick. Hundreds of thousands of microscopic, hair-like bristles cover the underside of each toe, each of which can potentially adhere to a surface using weak intermolecular forces. The combination of all of these bristles working together generates enough adhesive force to support the whole animal.
Knowing how geckos stick is just part of the story though. How did these complex adhesive toepads evolve? Scientists have long thought that sticky toes originated just once or, at most, twice in geckos. An alternative hypothesis though is that sticky toepads evolved again and again in different gecko species, a process called repeated or convergent evolution. To answer this question my colleagues and I first needed to understand how different gecko species are related to each other. We used DNA sequences from hundreds of gecko species to make a gecko family tree. We reconstructed the evolutionary history of adhesive toepads by tracing or mapping the occurrence of sticky toes onto this tree. We were amazed to discover that adhesive toepads were gained 11 times. Just as extraordinary, once gained, adhesive toepads were subsequently lost in 9 different gecko groups.
Gecko toepads therefore represent an example of repeated evolution. Biologists are particularly interested in this phenomenon because the independent gains and losses of sticky toes in geckos can be thought of as natural experiments conducted over deep evolutionary time. By studying these replicated patterns we can gain a better understanding not only of gecko biology but of the fundamental processes that drive evolution.