Systematics and evolution of Australia’s oldest lizard radiation: the Diplodactyline geckos

A project undertaken at the Western Australian Museum, South Australian Museum and the University of Adelaide, coordinated by Dr Paul Doughty

Australia has a famously diverse lizard fauna that has attracted the attention of evolutionary biologists for many decades. The Diplodactyline geckos are the third most speciose group of Australian lizards. They are endemic to Australasia and widespread across almost all environments. Current data suggest they have been in the Australian environment for far longer than most other lizard groups, which have migrated onto the continent from the north. However in spite of massive advances in techniques for inferring evolutionary history and species boundaries, this group has not yet been the subject of a comprehensive systematic and taxonomic assessment. Thus we are currently unsure of how particular groups relate to each other within the diplodactylines. In many cases there are also populations of geckos that are currently recognised as a single species that may mask the existence of several species. We aim to redress this situation by using multiple genetic loci to examine patterns of evolution and speciation within this group. The project will involve collaboration between the University of Adelaide and the Museums of West Australia and South Australia.

Recent results of the research have been the description of two new species of geckos. One species, Diplodactylus capensis, only occurs on the Northwest Cape of Western Australia. The other species, Lucasium bungabinna, occurs in the southern deserts of Western and South Australia.

We have also completed an analysis of date estimates for major divergence events with the Australian diplodactyline gecko radiation. A summary figure of these results is shown below. Our analysis suggests that the Australian diplodactyline gecko radiation is between 90-50 million years old. These dates are much older than those available for any other Australian lizard radiation and are comparable with famous Gondwanan groups such as marsupials and passerine birds. Indeed, it appears that diplodactyline geckos are one of the oldest vertebrate radiations endemic to the east of Wallace's Line.

 

Figure 1. Strophurus assimilis – a slender branch mimic with noxious secretions in the tail (photo – M. Hutchinson).

Figure 2. Pygopus lepidopus – an elongate legless terrestrial species (photo – M. Hutchinson).

Figure 3. Nephrurus vertebralis – a large-headed species that includes other geckos in its diet (photo – B. Maryan)

 

Figure 4. Male Cape Range Gecko, Diplodactylus capensis (photo - B Maryan)

 

Figure 5. Southern Sandplain Gecko, Lucasium bungabinna (photo - P. Oliver)