Tools to study tiny creatures

Field work in Antarctica searching for ground-dwelling invertebrates-2. Image: ??

PhD student Paul Czechowski sampling for meiofauna in Accidental Valley, the only ‘Dry Valley’ of the Prince Charles Mountains, continental Antarctica.

Studies of tiny, ground-dwelling terrestrial invertebrates in Antarctic ecosystems are driving the development of new tools and techniques for genetic analysis at the South Australian Museum. The information discovered has the potential improve our understanding of the impact of climate change.

The techniques, referred to as ‘molecular barcoding’, involve looking at key genes in invertebrates such as mites, nematode worms, tardigrades (commonly known as water bears) and rotifers (commonly known as wheel animals).

University of Adelaide postgraduate students Alejandro Velasco Castrillon and Paul Czechowski worked under the supervision of Dr Mark Stevens, Senior Research Scientist, Terrestrial Invertebrates at the Museum, to collect samples in the field and then develop the new techniques in the laboratory.

Alejandro collected soil samples across the three Antarctic coastal bases  Davis, Mawson and Casey  and studied the populations of invertebrates in each sample. He also looked at soil chemistry, soil dryness, land slope and the solar aspect of each ecosystem.

In contrast, Paul collected invertebrates from small ecosystems in Antarctica’s Prince Charles Mountains. This large rocky outcrop chain extends 600km inland from the Antarctic coast and is the largest ice-free area of the Australian Antarctic Territory. This geology of this area is reasonably well understood, but its biology has never been explored.

Field work in Antarctica searching for ground-dwelling invertebrates-3. Image: ??

Tiny springtails (Collembola) from beneath a stone are actually the largest land animals in Antarctica, here found in the Transantarctic Mountains, Antarctica.

The two students used slightly different approaches for their genetic analyses. Alejandro sorted through each of his soil samples to isolate the invertebrates  a slow and laborious process. He then extracted DNA and looked at the genes in each invertebrate population individually.

Building on this approach by avoiding the lengthy sorting step, Paul used entire soil samples for his DNA extraction procedures. Individual genes were analysed using specific markers known as primers, which allow specific DNA sequences to be found among a background of irrelevant material.

As the results of Alejandro’s studies were already completed, Paul was able to include his colleague’s samples in his own analyses as a sort of internal quality control step, to ensure his DNA detection methods were accurate and sensitive.

Together, the two studies formed a nice pairing for technique development. Once completed, they will form the basis of more rapid and high-throughput methods for genetic analysis of terrestrial invertebrates in mixed field samples.

From a broader perspective, Alejandro and Paul’s work also allows for comparative studies of the types and diversity of invertebrates that manage to survive and adapt to different environments in Antarctica. Investigating these relationships between life and its environment could provide valuable clues to better understanding the consequences of global climate changes.

Read the UNLOCKED story: Team Effort Brightens Future of Science (28 February 2013) featuring Alejandro's and Paul’s work.

This research was supported by grants from the Australian Antarctic Division, Mawson Trust, Mark Mitchell Foundation and the Royal Society of South Australia.

Field work in Antarctica searching for ground-dwelling invertebrates. Image: ??

PhD student Paul Czechowski sampling for meiofauna in the Prince Charles Mountains, continental Antarctica.