How Australia’s ancient forests became an arid zone

I didn’t plan to become a botanist, I just pursued activities that made me happy. Studying subjects that make you light up can guide you towards a career that doesn’t really feel like work because you find it fascinating.

During my childhood and teen years, I spent many weekends in the Australian bush around Vesper, West Gippsland, where my family had a farm. I was always interested in nature; I liked collecting flowers and noting the differences between species.

My research looks at the evolutionary relationships between species of Eremophila or Emu Bush. Like eucalypts and acacias, eremophilas are one of Australia’s largest plant groups, but they’re not as well studied. More than 270 species and subspecies occur across the Australian arid zone – the low-rainfall environment that covers most of the continent.

Until around 15 million years ago, the centre of Australia was wet and covered in forest. By comparing the DNA of eremophilas, we can reveal their evolutionary history and phylogenetic relationships – their family tree – and understand more about how the arid zone developed.

Knowing the distribution and relationships of contemporary species, we can predict the distribution of ancestral species. We see evidence that some lineages of Eremophila found exclusively in the arid zone are the result of recent, rapid expansions into dry areas.

Sciences & Technology

Taking Indigenous Australia to NASA

The name Eremophila comes from the Greek words for ‘lover of lonely or desert places’ - which perfectly describes where many species of Eremophila grow.

We can determine which genetic traits and physical features contributed to their success in adapting to a drier climate. We know that many species of Eremophila have a huge array of unique chemical compounds that tend to be concentrated in a resinous protective layer on the leaf surface.

These resins may reduce water loss, protect the leaves from thermal and UV damage, and act as a deterrent to herbivores eating them.   

For my PhD at the University of Melbourne, I used molecular techniques to establish each species’ unique DNA sequence,  the building blocks of genetic information that underpins all of life.

This allowed us to then figure out the relationships between Eremophila species.

My supervisors, Dr Daniel Murphy and Associate Professor Mike Bayly, devised the project. When I started it in 2013, I didn’t know much about eremophilas, but they quickly became a passion.

In some of the most remote and driest parts of the Australian desert, you can find them thriving and covered in flowers. Their diversity is astounding – from tiny purple insect-pollinated flowers to large, showy flowers visited by birds – and they have been used for thousands of years by Indigenous peoples.

It seems like a new species is described every few months, but some are found in limited areas, and many are rare or threatened.

Sciences & Technology

The challenge to discover our plant and fungi species

To compare Eremophila species, I sequenced the DNA in their nucleus and chloroplast. Like our cells, the nucleus is effectively the ‘control’ centre, housing most of the DNA.

Chloroplasts are structures in plant cells that contain chlorophyll and play a key role in photosynthesis.

They contain their own DNA – separate to the cell’s nucleus – which codes the genes involved in photosynthesis and other metabolic processes.

I used a technique that was new at the time, called shotgun sequencing. It involves shearing all of the DNA from the cell into small, random fragments and then sequencing the lot.

Different parts of the genome occur in different amounts and the regions with more copies of DNA (i.e. the full chloroplast genome and nuclear ribosomal DNA) drown out the weaker signals from the rest.

Sequencing technology is advancing rapidly, so my project went from looking at tiny portions of a plant’s chloroplast DNA, to sequencing the full chloroplast genome of approximately 150,000 base pairs (where each base pair forms a ‘rung’ in a ladder-shaped DNA molecule).

Sciences & Technology

From art restorer to DNA explorer

I'm still publishing work from my PhD, while building on it with even newer techniques and looking at other plant groups, including eucalypts. There’s more research into eremophilas happening now, but still only a few people doing major phylogenetic studies.

I hope that my research will introduce more people to the importance of phylogenetics.

I’ve just started a five-year role as a Pauline Ladiges Plant Systematic Research Fellow. The position is shared between the University of Melbourne and the Royal Botanic Gardens Victoria, so I can collaborate with botanists from both institutions.

I’ll continue to work on eremophilas and eucalypts and I’m free to choose how to spend the remainder of my time, which is a fantastic opportunity. I'm in the planning phase of ‘Where do I want this to go?’.

I would love to incorporate more medicinal, chemical and Indigenous perspectives into my research. Having more Indigenous voices contributing to our understanding of Australian plants would be wonderful.

Aboriginal people have used and understood these plants for millennia.

Incorporating Indigenous knowledge, including recognising Indigenous names and uses for particular species, alongside a Western scientific perspective, is invaluable. 

As told to Taya Ferraro