ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Gabriella Sparkes is an author on ‘ Sex-specific performance, trade-offs and trait repeatability across the lifetime of the world's largest semelparous mammal (Dasyurus hallucatus)’, published in JEB. Gabriella is a PhD student in the lab of Robbie Wilson at the University of Queensland, Australia, investigating how movement and performance shape survival and reproductive success in wild animals, from life-history strategies and performance trade-offs to fine-scale behaviour and locomotion of animals navigating complex landscapes.
Gabriella Sparkes
How did you become interested in biology?
Australia has so many weird and wonderful animals! I don't think I fully appreciated this until a bit later in life, probably into my final year at university. All these strange, pouched, hopping, climbing, spikey, furred and scaley creatures most of us Aussies just accept as ‘normal’ are even more fascinating when you get to understand how they behave, move and survive. I think northern quolls epitomise this so well, and totally hooked me into the complicated world of biology, ecology and evolution. Now, every time I go into the field or travel, I get to look at the world with fresh eyes and a real curiosity about how and why these animals do what they do.
Describe your scientific journey and your current research focus
I started my research career studying northern quolls – Australia's largest semelparous mammal – exploring how their extreme breeding strategy shapes physical performance. Males push themselves to their absolute limits during a single, high-stakes breeding season, while females must survive multiple years and endure intense competition. I investigated how sprint speed and bite force change over their lifetimes and whether trade-offs exist between these traits. Now, my PhD focuses on koalas, where I use bio-loggers to track their movements and understand how they navigate their environment−particularly when making risky transitions along the ground from tree to tree. I combine traditional behavioural ecology with modern tracking technologies to reveal patterns of movement and decision making that are difficult to observe directly. By studying species with vastly different ecological challenges, my work aims to understand how movement is shaped by evolutionary pressures, environmental constraints and physical and behavioural trade-offs.
Male northern quoll (Dasyurus hallucatus) caught on Groote Eylandt in the breeding season. Note the beginning of the loss of fur around the hindlegs due to male–male combat and declining condition, and general palpable aggression! Photo credit: Miranda Rew-Duffy.
Male northern quoll (Dasyurus hallucatus) caught on Groote Eylandt in the breeding season. Note the beginning of the loss of fur around the hindlegs due to male–male combat and declining condition, and general palpable aggression! Photo credit: Miranda Rew-Duffy.
How would you explain the main findings of your paper to a member of the public?
Northern quolls have one of the most extreme breeding strategies of any mammal. Males invest all their energy and resources into a single, frantic breeding season – competing fiercely with other males, and covering vast distances to find females – before completely burning out and dying. Their bodies break down under the stress, and by the end of the season, they are exhausted – slower, weaker and in significantly poorer condition. In contrast, females survive multiple years and must raise their young alone, but they also pay a heavy price. During breeding, they endure relentless male aggression and competition with other females for food and shelter. Afterward, their bite force increases – potentially as a response to these pressures – helping them defend themselves and their young. Despite these intense demands, we found no evidence that bigger biters are slower sprinters, suggesting these traits evolve independently. Our study reveals how extreme breeding strategies shape physical performance in the wild and highlights the massive survival costs animals pay for reproductive success.
What do you enjoy most about research, and why?
I love that research is just an extension of our curiosity about the natural world – you get to peek behind the curtain and ask what animals do in the wild. What's better is that I get to combine traditional methods of biology and behavioural ecology research, like tracking, field observations and experiments, with modern, high-tech tools such as bio-loggers and high-speed cameras. What this means is that we get to quantify movement and behaviour in a way that was not possible even 10 years ago. Whether it's a koala carefully choosing when to move between feeding trees or a quoll running itself into the ground during the breeding season, I love that I get to reveal the hidden mechanics of animal lives and how they interact with their world.
What is the most important lesson that you have learned from your career so far?
The most important lesson I've learned is that good research isn't just about finding answers – it's about asking the right questions. It's easy to get caught up in data and methods, but at the core of it all is curiosity. The researchers I admire most – mentors, supervisors and leaders in my field – share a deep fascination with the natural world. They remind me that before we can figure out how to conserve or protect a species, we first need to understand it – how it functions, moves and interacts with its environment.
I've also learned that research rarely goes to plan, and that's not a bad thing. Whether it's bio-loggers failing in the field or quolls refusing to cooperate, working with wild animals is full of surprises. Being adaptable, thinking creatively and rolling with the unexpected are just as important as technical skills. At the end of the day, the best science comes from staying curious, asking good questions, and sometimes just watching and learning.
Gabriella Sparkes's contact details: School of the Environment, University of Queensland, St Lucia, QLD 4072, Australia.
E-mail: [email protected]
