AsianScientist (Dec. 30, 2014) – By mimicking the red and green colors of falling leaves, Bornean lizards avoid falling prey to birds whilst gliding, research published in Biology Letters has found.
The work suggests that populations of the gliding lizard, Draco cornutus, have evolved extendable gliding membranes 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—call patagia—which allow them to glide between trees in their territories.
The study was conducted by PhD student Ms. Danielle Klomp, based at the University of Melbourne and the University of New South Wales (UNSW) with supervisors Dr. Terry Ord (UNSW) and Dr. Devi Stuart-Fox (University of Melbourne) and collaborator Dr. Indraneil Das from the University of Malaysia.
The team traveled 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.
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 said. Therefore, the team determined how the colors would be perceived by a predatory bird and found that the gliding membrane color would be indistinguishable from a falling leaf in the same forest.
“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 said.
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,” Klomp said.
“Perhaps these populations may have originally had the same gliding membrane colours but as they have moved into different forest types their colours have adapted to closely resemble the colours of falling leaves in the different forests, known as divergent evolution.”
The article can be found at: Klomp et al. (2014) Marked Colour Divergence in the Gliding Membranes of a Tropical Lizard Mirrors Population Differences in the Colour of Falling Leaves.
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Source: University of Melbourne.
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