‘ Phyllurus gulbaru is estimated to be restricted to a mere 14km 2 .’
locations where two species occur sympatrically , each habitat supports just a single species . This suggests either that the various species outcompete each other , so that only one can hold sway in a given habitat , or that populations have become restricted to habitat pockets and evolved in isolation , with consequent endemic adaptation giving rise to diverse species .
Molecular genetic studies have revealed that leaf-tailed geckos are , in fact , ancient lineages : the split between the two major genera , Saltuarius and Phyllurus has been dated as occurring sometime between 58-74 million years ago , while Orraya evolved even earlier . Despite looking fairly similar , even the species within a given genus represent ancient evolutionary lineages : for example , Phyllurus species from mid-east Queensland are estimated to have diverged 31-38 million years ago , and this is believed to have been the result of fragmentation and contraction of a formerly continuous rainforest in the area . Evidence suggests that the divergent lineages are a reflection of contractions and isolation of rainforest over geological ( and thus evolutionary ) time . Australia was once covered in rainforests , however , with the movement of the continent owing to plate tectonics , coupled with the effects of historical climate change , the environment became increasingly arid . Populations would therefore have become stranded in small , moist pockets of habitat such as those to be found in rocky gorges or on mountain tops , meaning that today two adjacent mountains may harbour their own distinct species .
‘ Phyllurus gulbaru is estimated to be restricted to a mere 14km 2 .’
One species of leaf-tail may , however , be described as ‘ synanthropic ’ and has been known to occupy the homes and gardens of Sydney residents since the first European settlement . Phyllurus platurus is endemic to the Sydney basin , and is one of the most common and accessible of the leaf-tailed geckos . Two of the most eminent herpetologists in Australia , Dr Paul Doughty and Dr Rick Shine , have published a thorough investigation into the natural history of this saxicolous species entitled ‘ Life in two dimensions : natural history of the southern leaf-tailed gecko , P . platurus ’. Females are larger than males , attaining larger mean and maximum body sizes , and having relatively longer and thicker abdomens . This form of sexual dimorphism is fairly common in most taxa other than mammals , and probably relates to being able to accommodate clutches of relatively large eggs . Gravid females are likely to be disadvantaged by their distended abdomens , as this may limit their ability to hide in the rock crevices they use for habitat and protection from predators . Hatchlings are remarkably large , with a snout-to-vent length of 33-41mm , which is already more than one-third that of the mother .
In recent years a spate of new species have been described . Despite being a charismatic component of Australian herps , the first taxonomic assessment of leaf-tailed geckos was not conducted until 1990 , as part of a larger study on the phylogenetic systematics and biogeography of the Carphodactylini . Only four species , all within the genus Phyllurus , were recognised at the time . Since then , the number of recognised leaf-tailed gecko species has more than quadrupled .
Top left : leaf-tailed geckos ’ rugose bodies add to the creation of a lichen-encrusted appearance . Image by Michael Cermak . Below : ‘ The gecko disappears into the texture of the bark ....’