Following on from the student hand-in trifecta post, here are two more Masters projects recently completed by students working in the museum’s Natural Sciences Department. Both students performed genetic analysis on local lizard species.
Pete Smissen examined the geographic movement of the Lace Monitor (Varanus varius) over time. About 25,000-20,000 years ago, Australia experienced its Last Glacial Maximum, when the climate was colder and drier than it is currently.
Pete's fieldwork with Lace Monitors. Left: Weighing an animal in the field. Right: A Lace Monitor basking in a sunny tree.
Image: Peter Smissen
Source: Peter Smissen
Analysing mitochondrial DNA (which is only passed down maternal lines), Pete found that there are three genetically distinct groups of Lace Monitors in Australia that have been evolving independently since the time of the Last Glacial Maximum. This suggests that the species persisted through these cold times in small refugia then dispersed broadly as temperatures increased. When he looked at fast-evolving nuclear DNA, (which is inherited from both parents), he found similar population clusters across Australia, but little genetic structure in a smaller geographic area in Gippsland. This lack of structure is a different pattern to that found in many other species, but is consistent with Lace Monitors being large, mobile, generalist animals.
Luisa Teasdale examined the variable colouration found in male Tawny Dragons (Ctenophorus decresii). Some males have vibrant orange patches on their throats while others are quite drab.
The four distinct throat colour morphs in Tawny Dragons.
Image: Luisa Teasdale
Source: Luisa Teasdale
By analysing digital photographs for colour and pattern combined with genetic tecniques, she found evidence that there are four distinctly different morphs that seem to be genetically clustered. This suggests that even though there is one interbreeding population, the lizards breed preferentially with their own morph. Her work poses some interesting questions about how the four morphs differ in other respects, such as behaviour or life history, and what keeps them separate even within the same population.
Congratulations to Luisa and Pete for completing their fascinating projects!
Information for prospective students
Lizards of Victoria infosheet series