How flies can help us predict the future

Dr Vanessa Kellermann, evolutionary biologist, Monash University, Melbourne

Dr Vanessa Kellermann (credit: L’Oréal Australia)Our planet’s climate is changing. How will bees cope—will they still be able to pollinate our crops? Will dengue and malaria–carrying mosquitoes spread south?

Vanessa Kellermann is working with native fruit fly species from Tasmania to tropical Queensland to find out. She has already demonstrated that tropical flies are more vulnerable to change in the long term. They don’t have the genetic capacity to evolve quickly. Now, with her L’Oréal For Women in Science Fellowship, she will explore how flexible they are in the short term—how individual insects can respond to change during their lifetimes.

“No one sets out to study flies,” she says. But they are perfect for asking basic questions that will allow us to create models of evolution and help people—from farmers to health professionals—plan for change.

When Dr Vanessa Kellermann tells people she studies flies, there’s an almost automatic assumption that she’s working to get rid of them. In fact, it’s quite the reverse. Vanessa would consider her research a success if her flies hung around for many more millions of years, along with most of the other plants and animals on Earth.

Vanessa is using the hundreds of different species of native fruit flies (Drosophila) that occur up and down the east coast of Australia as model organisms for investigating the capacity of species to adapt to climate change. She wants to develop techniques to predict which species are at risk of extinction and which are likely to spread.

Not only would such knowledge help us manage our future biological environment and save species from extinction, it would also allow us to prepare for changes in the distribution of beneficial organisms, such as crops and their pollinators, and harmful organisms, such as agricultural pests, parasites and those that cause disease.

Vanessa started by looking at how genetically well-equipped Drosophila species are to adapt to climate change, and she found that the answer depended on their ecology—the kind of environment in which they lived—and their evolutionary history. Tropical species, for example, do not move out of their highly humid environment, in contrast to the more widely distributed temperate species. The more we know about the genetic traits that determine the current distribution of species, the better we will be able to predict their likely future reaction to changes in climate.

But genetic changes typically occur over many generations. Even short-lived species such as fruit flies may be too slow to adapt genetically to the current rapid changes in climate. So now Vanessa wants to extend her studies to changes that occur within a single generation—the flexibility of physiology known as plasticity.

To help her pursue this important work, Vanessa, an Australian Research Council (ARC) Discovery Early Career Research Award (DECRA) fellow in the School of Biological Sciences at Monash University, has been awarded a $25,000 L’Oréal Australia and New Zealand For Women in Science Fellowship.

She will use the money to employ a research assistant to help her with the “crazy things” she used to do—experiments that demand 24 hours of constant monitoring, for instance. As a new mother, she is beginning to find such things are behind her.

(Video also available in HD and without music – email: toni@scienceinpublic.com.au)

The distribution of most of the world’s organisms—plants, microbes, insects, reptiles—is affected directly by climate. “Because these organisms cannot regulate their temperature, climate plays a key role in shaping where they live. Previous studies suggest there is a lot of variation in the ability of species to resist cold, but not heat. With my flies, for instance, it doesn’t seem to matter if a species comes from Denmark or Brisbane—they tend to have similar heat tolerance.”

In exploring how much of this capacity to change was innate, Vanessa collected species from along the length of the east coast—from southern Tasmania to Far North Queensland—brought them back to her laboratory and reared them all at the same temperature under identical environmental conditions. She then tested them under steadily increasing temperature in a water bath to find what temperature sent them into a coma, and how long it took.

One thing she found was that species that were closely related on the evolutionary tree tended to show similar patterns, to behave as a group. This suggests that evolutionary history, and how closely groups of genes are related, also affects genetic capacity.

Now she wants to extend her studies to plasticity. “The thinking is that if the speed of climate change is quicker than genetic change, then perhaps immediate changes in the body’s thermal tolerance can hold the fort, while evolution catches up.” One hypothesis she wants to test is whether individuals of tropical species show less capacity to change than those of temperate species.

But measuring such plasticity is a lot more difficult than measuring innate characteristics. Already, some of the methods she hoped to use—such as monitoring the level of activity under different heat conditions, using the number of times the fruit flies intersect a light beam—have proved problematic.

Initially, she’ll probably go back to a variation of her method for investigating genetic capacity. This time, however, the flies of 20 different species will be split into batches each reared at different temperatures—15 °C, 17 °C, 19 °C and so on. These can then be checked for heat resistance, development time and viability. If a species is plastic, the temperature of its rearing will change its response, which thereby broadens its capacity to survive under different environmental conditions.

“Plasticity is a real hole in our knowledge of adaptation. No one has really set out to examine the variation in plasticity over so many species. The L’Oréal Fellowship will allow me to scope out the project and determine what works.”

The practical rewards should be significant. The main aim, Vanessa says, is to begin to predict the response of species to climate change. And that should help people like farmers. Insects play a critical role in agriculture, both in pollinating and attacking crops, and the crops themselves will respond to climate change. Such predictions should also assist health authorities to assess the spread of diseases such as dengue fever carried by mosquitoes whose distribution is likely to change. “Eventually, we want to be able to develop models of the changes in species distributions under climate change.”

It seems that some people may have to revise their opinion of the usefulness of flies.

Qualifications

2008PhD (evolutionary biology), The University of Melbourne
2003Bachelor of Science (Honours) (genetics), La Trobe University, Melbourne

Career highlights, awards, fellowships, grants

2014–presentARC Postdoctoral Research Fellow, Discovery Early Career Research Award, Buffering climate change—Predicting the evolution of phenotypic plasticity, Monash University, Melbourne
2014Theo Murphy High Flyers Think Tank: Climate change challenges to health; Risks and opportunities, hosted by the Australian Acedmy of Science
2012–2013Postdoctoral Researcher,Linking genomes to adaptive variation in 20 Drosophila species, Monash University, Melbourne
2011Speaker, Identifying phylogenetic and ecological constraints limiting species distributions: a 100 Drosophila species comparison, 13th Congress for the European Society of Evolutionary Biology, Tubingen, Germany
2009–2011Postdoctoral Fellow, Determining the role of ecology vs. phylogeny in the evolution of stress resistance: a 100 species
2010Invited presentation, Evolution of temperature and dehydration tolerance in Drosophilids. Society for Experimental Biology, Prague, Czech Republic
2008–2009Research Associate, Examining the potential for evolutionary responses in ecological traits in tropical and temperate Drosophila, Monash University, Melbourne
2008Research Associate, Exploring candidate genes for stress resistance in Drosophila species, The University of Melbourne
2006Melbourne Abroad Travelling Scholarship to present at the Society for the Study of Evolution conference, Stonybrook, New York, USA

Top five publications

Kellermann VM, van Heerwaarden B, Sgrò CM and Hoffmann AA (2009) Fundamental evolutionary limits in ecological traits drive Drosophila species distributions, Science 325: 1244–1246. (Impact factor 32.5, 164 citations)

Kellermann VM, Overgaard J, Hoffmann AA, Kristensen TN, Flojgaard C, David JR, Svenning JC and Loeschke V (2012) Upper thermal limits of Drosophila are linked to species distributions and strongly constrained phylogenetically, Proceedings of the National Academy of Sciences 109: 16228–16233. (Impact factor 10.47, 38 citations)

Kellermann VM, Loeschke V, Hoffmann AA, Kristensen TN, Flojgaard C, David JR, Svenning JC and Overgaard J (2012) Phylogenetic constraints in key functional traits behind species’ climate niches: Patterns of desiccation and cold resistance across 95 Drosophila species, Evolution 66: 3377– 3389. (Impact factor 5.6, 33 citations)

Kellermann VM, van Heerwaarden B, Hoffmann AA and Sgrò CM (2006) Very low additive genetic variance and evolutionary potential in multiple populations of two rainforest Drosophila species, Evolution 60: 1104–1108. (Impact factor 5.6, 58 citations)

Schilthuizen M and Kellermann VM (2014) Contemporary climate change and terrestrial invertebrates: evolutionary versus plastic changes, Evolutionary Applications 7 (1): 56–67. (Impact factor: 4.7, 8 citations)

Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)
Dr Vanessa Kellermann (credit: L’Oréal Australia)