How I overlooked this Christmas Eve 2014 gem previously I’ll never know, but it’s too good not to share. So by way of a belated Christmas present, here goes.
We may be used to animals that mimic plant parts, such as leaves or twigs, but those are usually static mimicries. A study of gliding lizards (yes, miniature ‘dragons’ that do sort of ‘fly’) in Borneo by Danielle Klomp et al. takes leaf-mimicry by animals to a new level. They found that the patagia (the extensible, rib-supported membranes that enable the owners to glide between trees) of different populations of Draco cornutus differed in colour. They also realised that those colour differences matched the different colours of the freshly fallen leaves typical of the vegetation where the lizards lived – reddish amongst mangroves, and green and dark brown in the rainforest. But, and importantly, the colour-matching was in terms of how the leaf colours would appear to the eyes of birds that might eat the lizards.
The team thus surmise that patagial colouration mimics the colour of falling leaves so when in flight – and presumably more vulnerable to predation – the lizards might be ignored by birds as if they were falling leaves. I suppose a direct way of testing this hypothesis is to translocate mangrove lizard populations to the rainforest – and vice versa – to see how camouflaged the aerial reptiles are in a different environment. But I suspect there may be ethical prohibitions on that sort of experiment.
However, whilst this feat is certainly impressive, maybe the leaf-mimicking honours should go to a plant, the woody vine Boquila trifoliolata (a monotypic genus in the amazingly named family Lardizabalaceae, the first 6 letters of which are curiously an anagram of … lizard..!), which is able to mimic the leaves (‘in terms of size, shape, color, orientation, petiole length, and/or tip spininess’!) of the host plants over which it scrambles, and which can mimic several hosts simultaneously !!! ‘Leapin’ lizards!’, as one Little Orphan Annie might say. Indeed!
[For more on mimicry by plants, we recommend Spencer Barrett’s review Mimicry in Plants in Scientific American. For a blog entry about the Bornean fallen-leaf mimics, see Ambika Kamath’s item from August 2014, which predates the published article by several months. And to find out how to add an ‘aura’ to a poster, it’s worth looking at Danielle Klomp’s blog – Ed.]