Sticky toes help lizards live high in the trees

Anyone who’s watched a lizard scale a cliff, building or tree seemingly without effort  knows they have some serious climbing skills. Many lizards have this remarkable climbing ability, with tiny claws that cling to a variety of surfaces. Some lizards that live high in the tree tops have evolved special anatomy – sticky toes that are perfect for climbing.  

Geckoes, skinks and Anolis lizards each independently evolved sticky toe pads. There are, however, hundreds of other lizards adapted to life in the trees, many of which do not possess these special sticky toes. 

Scientists at Washington University set out to investigate whether sticky toe pads confer an advantage to the lizards that possess them. Using a previously published database of habitat use, the researchers were able to analyze the evolutionary relationship of lizards that live in trees. 

Interestingly, the scientists found, lizards evolved the ability to live in trees hundreds of times, with thousands of species living in trees. 

Even more fascinating, sticky toe pads evolved only after lizards already lived in trees – it wasn’t a prerequisite. Study co-author James Stroud explained the advantage the team found in sticky toes.

“There are hundreds of lizards living in the trees, but over evolutionary time many of those species end up leaving for life on the ground because, presumably, they interact with these padded lizards that have a greater advantage,” said Stroud.

Despite the fascinating conclusion that sticky toe pads to infer an advantage to tree living lizards, study co-author Aryeh Miller said there’s more research still to be done.

“Analyzing evolutionary relationships can tell us a lot, but next we need to go out into nature – to see what parts of the environment the lizards use and why these evolutionary relationships exist,” said Miller.

The study is published in the journal Systematic Biology.

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By Zach Fitzner, Earth.com Staff Writer