In Insights we discover the story – and the people- behind a recent publication in Functional Ecology. What inspired the authors and how did the project develop leading to the final publication? And what are the implications of their research for the scientific community and society in general? In this week’s Insights, Rebecca Koch, post-doc from Monash University, Australia talks about her work and her recent Review paper with Geoffrey Hill, on the resource trade-off hypothesis in avian ornamental coloration.
How has your career developed over the last few years and what is your current position?
I am still surprised by my current position: I am a postdoc in the Dowling Lab at Monash University, where I study evolutionary genetics in fruit flies. I never imagined that I would study any organism less charismatic than birds, but I decided that my first postdoc would be a perfect opportunity to experience a completely different side of evolutionary biology. I hope to pursue some of the same questions about mate choice and individual quality as I have addressed in birds, but now I have access to thousands rather than tens of individuals
How did you get involved in ecology and evolution?
I’ve enjoyed watching birds for most of my life, and when it came time to start narrowing down career options, I couldn’t help but gravitate toward studying bizarre bird mate choice displays. My first “real” research project was on understanding the strut displays of male greater sage-grouse, perhaps one of the most nonsensical displays I can imagine. My interest in bird coloration, however, actually started in high school: quite coincidentally, I performed a high school research project on house finch color variation, based largely on the work of the same professor (Geoff Hill) who eventually became my PhD advisor and coauthor!
Can you briefly describe your review and say why you decided a review on the resource trade-off hypothesis was timely?
Our review focuses on the predominant framework used to explain condition-dependent signals in carotenoid-based coloration: the resource trade-off hypothesis. This hypothesis is one of those concepts that is generally understood and appears in various forms across the carotenoid literature, but has never been properly defined and discussed. I think that this review is actually overdue because researchers have been studying honest carotenoid signals under the framework of resource trade-offs for decades, but without a common understanding of what that framework really is (and what it means). As a result, I think that the carotenoid signalling literature has become rather complicated, sprawling, and inconclusive. In our paper, we work to bring together the fundamental assumptions of the resource trade-off hypothesis and how best to test them.
What were your main findings and how does your review help further research efforts?
While our review is not intended as a critique of the resource trade-off hypothesis per se, I hope that it draws attention to some important gaps in knowledge and methodology that I think are keeping us from really moving forward in the study of carotenoid-based colour signalling. In the review, we repeatedly argue that researchers need to quantify and track carotenoid molecules as they travel throughout the animal body. Given that almost all studies on the condition-dependence of carotenoid ornaments hinge on assumptions of resource limitation and costly allocation, it may seem obvious that we need to quantitatively ascertain limitation and allocation of those resources; however, existing studies have instead relied on indirect correlations to estimate carotenoid quantities. I hope that our review will spur at least one research group to radiotrack carotenoid molecules under different conditions (sick vs. healthy birds, for example) and help to finally understand how (and where) birds use the pigments moving throughout their bodies.
Were you surprised by any of your results after analysing your data?
I was surprised to find how the vast majority of research in this topic has been performed on just a limited number of species, often driven by a handful of productive research groups. I wouldn’t say that this is a problem, exactly, or even that it is unusual within science. But we generally consider our understanding of carotenoid coloration in birds to be thorough … and how thorough can it really be when so much of what we know seems based on zebra finches and house finches?
What is the broader impact – outside avian ecology – of your paper?
The question of how carotenoid-based coloration can be an honest signal of internal condition is particularly exciting because it often leads to tests of how (and whether) dietary carotenoid pigments serve a physiological benefit. While coloured birds are several taxonomic steps removed from, say, humans, I think that it is still extremely interesting to delve into whether carotenoids really are important antioxidants or immune supplements in animals. Even though the focus of these studies is understanding coloration, the results can be quite relevant to understanding dietary supplements, antioxidant defences, and overall individual health.
What do you like most about being an ecologist? What could you happily do without?
I most identify with the behavioural side of ecology, and from that perspective, I think that the respect we gain for the complexity of animal lives is invaluable. I used to worry that studying a species would make me start to loathe it—that I would start seeing birds, for example, as data points rather than beautiful creatures. But, I have found that the opposite is true. The more I understand about the strange and wonderful things that animals do, the more I appreciate how lucky we are to have a chance to share the world with them.
Now that I am taking a hiatus from directly studying avian ecology, I can say that having a deep passion for my study organism is not always helpful. As a wide range of ecological disciplines move toward using physiological and genetic techniques, it can be tough to poke and prod the animals we love. (I don’t have that problem with my fruit flies!)
What achievement are you most proud of?
I kept as many as 150 canaries alive at the aviary on my graduate school campus for several years. That was a far more challenging task than it initially seemed! Now, I’m happy to say that one of my favourite pairs of orange canaries is living a lovely life of retirement in my parents’ house.
How do you balance work and down-time?
Particularly since finishing my PhD, I have worked to keep my work at work—that means less time working odd hours at home. The upside of this is that I’m forced to keep creative with non-work activities to stay busy in the evenings and over weekends. Moving to a new country (Australia) has opened up an exciting new array of bird species to track down, so I try to head out with my corgis and find some colourful parrots when I can. Otherwise, I’ve taken up swimming with a local team, which is therapeutic as well as humorous as I try to beat the 12-year-olds swimming next to me! I think that one of the best parts of an academic job is that we generally have access to great fitness centers (and pools), which can be so important for mental as well as physical health.
You can read “Do carotenoid‐based ornaments entail resource tradeoffs? An evaluation of theory and data” here and a free plain language summary of the paper here.