Red and green 'wings' keep these lizards safe
December 24th, 2014 Posted by Nerissa Hannink-Melbourne
"It's a cool finding because these gliding lizards are matching the colors of falling leaves and not the leaves that are still attached to the tree," says Danielle Klomp. (Credit: Devi Stuart-Fox)
In Borneo, a kind of gliding lizard's red and green colors offer safety from predation by birds.
New research suggests that populations of the gliding lizard, Draco cornutus, have evolved extendable gliding membranes, like wings, which closely match the colors of falling leaves to disguise themselves as they glide between trees in the rainforest.
Found throughout Southeast Asia, Draco is the only living genus of lizard with extendable gliding membranes—called patagia—that allow them to glide between trees in their territories.
(Credit: Devi Stuart-Fox)
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Published in Biology Letters, the study was conducted by PhD student Danielle Klomp, based at the University of Melbourne and the University of New South Wales. Her supervisors, Terry Ord of the University of New South Wales and Devi Stuart-Fox of the University of Melbourne, worked on the study, as well, as did Indraneil Das of the University of Malaysia.
The team travelled to Borneo and observed two populations of a gliding lizard that have different colored gliding membranes and occupy very different habitats.
One population has red gliding membranes, which match the color of the red falling leaves of their coastal mangrove forest habitat. The other population has dark brown and green gliding membranes, which match the colors of falling leaves in their lowland rainforest habitat.
Bird vision
The researchers determined how a predatory bird would perceive the colors and found that the gliding membrane color would be indistinguishable from a falling leaf in the same forest.
Birds can see ultraviolet light as well as the colors that humans see, so it is important to take into account how closely the colors would actually match to a bird, Klomp says.
"It's a cool finding because these gliding lizards are matching the colors of falling leaves and not the leaves that are still attached to the tree.
"In the mangrove population the leaves on the trees are bright green, but turn red shortly before falling to the ground, and it is this red color that the lizards mimic in their gliding membranes.
"This allows them to mimic a moving part of the environment—falling leaves—when they are gliding." Klomp says.
Lizard footage
The team also filmed hours of gliding lizard behavior to observe how often the colors were displayed in communication with other lizards.
"We found that both the red and green/brown gliding membranes do seem to have evolved specifically to resemble the falling leaves in each population's particular habitat, and are rarely used for communication," says Klomp.
"Perhaps these populations may have originally had the same gliding membrane colors but as they have moved into different forest types their colors have adapted to closely resemble the colors of falling leaves in the different forests, known as divergent evolution."
Source: University of Melbourne
Original Study DOI: 10.1098/rsbl.2014.0776
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