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. Carmen da Silva is an author on ‘ Temperature and precipitation explain variation in metabolic rate but not frequency of gas exchange in Fijian bees’, published in JEB. Carmen conducted the research described in this article while a Postdoctoral Researcher at Monash University and Macquarie University, Australia, working with Lesley Alton and Vanessa Kellermann. Carmen is now a Macquarie University Research Fellow, working with Dr Oliver Griffith and Prof. Ajay Narendra at Macquarie University, Australia, investigating the functional basis of organismal and ecosystem resilience to global change.
Carmen da Silva
How did you become interested in biology?
It was somewhat inevitable that I would become interested in biology. Both of my parents are biologists and most holidays and dinner table discussions had a biology theme as I was growing up. While my parents were a great inspiration (e.g. attending a field trip on Lizard Island as a teen was a real highlight) it has been important to develop as an independent biologist myself. Moving away from South Australia to Queensland, Victoria and New South Wales was essential to form my own ideas and research program.
Describe your scientific journey and your current research focus
I actually started my scientific journey (honours project) on the Fijian bee system (same as this paper) with Prof. Michael Schwarz at Flinders University in South Australia. He is a bee and sociality expert, and he really ignited my interest in bee evolutionary ecology. However, I ended up doing my PhD on thermal physiology in intertidal fish at The University of Queensland (which was so much fun – I had field trips on Heron Island, North Stradbroke Island and the Sunshine Coast, attended conferences in Hobart and France, and made so many long-term collaborations and friends). This experience allowed me to build the skills required to start a research program on evolutionary physiology, but back on my beloved bees in Fiji on an Endeavour Postdoctoral Scholarship (4 months). While I was in Fiji, I interviewed for a postdoc with Prof. Sarah Diamond at Case Western Reserve University, USA; I was lucky enough to get the job, but then COVID-19 happened, and I couldn't move to the USA. So, I ended up doing two postdocs at once: I worked part time with Sarah on butterfly range shifts/evolutionary ecology and part time with Dr Vanessa Kellermann and Dr Ros Gloag at Monash University on native bee evolutionary physiology. It was kind of crazy trying to do two different postdocs at once but I'm so glad I was able to build relationships with both teams and get to do exciting work on both systems. Now I'm a Macquarie University Research Fellow examining how native bees are evolving with climate warming and drying, and examining sub-lethal impacts of climate change on performance such as flight speed.
How would you explain the main findings of your paper to a member of the public?
Climatic factors like temperature and precipitation are hypothesized to shape species physiological traits (like their metabolic rate, thermal tolerance and ability to survive in dry environments). However, how climate shapes species traits and geographic ranges is still up for debate – especially in tropical insects! We tested the metabolic cold adaptation hypothesis (MCA), which predicts that species that live in colder environments should have higher metabolic rates than species that live in warm environments so that cold adapted animals can function when physiological rates are slowed by cold temperatures. We also tested the hygric hypothesis, which predicts that insects that live in dry environments should hold their breath to avoid water loss more than insects that live in wetter environments. Across an elevational gradient in Fiji, we found that bees that live in colder environments (higher elevations) do have higher metabolic rates than bees that live at warmer (lower elevations), supporting the MCA hypothesis, but that precipitation also explains variation in metabolic rate. We did not find any evidence to support the hygric hypothesis, but we did find an interesting pattern between the way that metabolic rate and breathing pattern co-vary across the elevational gradient, where low elevation bees breathe faster for their metabolic rate than high elevation bees.
Finding support for the MCA hypothesis across a relatively narrow thermal gradient in Fijian bees was somewhat surprising because we did not expect tropical bees to require adaptations to help them survive in cooler temperatures. This finding is exciting as it showcases that energy responses to even small changes in temperature are important in adaptation. Lastly, finding that metabolic rate and breathing pattern co-vary across the elevational gradient is an important step towards understanding species evolution more holistically as a mosaic of traits.
Why did you choose JEB to publish your paper?
Back in 2019 I was awarded a Travelling Fellowship from The Company of Biologists (JEB) to help support my Fijian bee research. This funding allowed me to conduct fieldtrips into the highlands and assess Fijian bee physiological traits. Our first manuscript from this work was published in JEB in 2021 (‘Climate change and invasive species: a physiological performance comparison of invasive and endemic bees in Fiji’, doi:10.1242/jeb.230326). I thought that the current manuscript testing the metabolic cold adaptation hypothesis and the hygric hypothesis in the same system would be a fantastic follow up paper in the same journal. I was pleased that our 2021 article was the most cited paper in the journal that year, and I hope our current article is also of interest to a broad readership.
What is the most important lesson that you have learned from your career so far?
This is both a personal and a scientific tip – slow down! I am always eager to jump into new projects and activities. But, I've learnt the hard way that proper planning and experimental design is so important and makes the rest of the project/statistics/activity much easier and more satisfying in the long term. Another important lesson to remember is that it is not personal when you don't get a grant or a paper gets rejected. While this lesson is frequently discussed, it is an important one to remember. We are in a career where a thick skin is needed because everyone experiences rejection, unfortunately usually more than acceptance, even those at the top of their field. We need enthusiastic and passionate people in our field, and it helps to keep going if you remember it's not personal during times of rejection.
What's next for you?
I've just become a mum so my research journey changed pace a bit recently. I've taken the last 9 months off and still have a few more months of maternity leave. I'm going to have to learn how to balance motherhood and academia, although I hope I can also intertwine them like how I grew up. I've already got some plans to take my son on a field trip to Cape York in Far North Queensland to measure native bee flight performance at different temperatures in 2026 as part of my sublethal impacts of climate change project. While he will be quite young on this trip, I hope that I can teach him to care about and for our amazing ecosystems.
Carmen da Silva’s contact details: Macquarie University, North Ryde, NSW 2113, Australia.
E-mail: [email protected]
