ECR Spotlight – Jessica Li Free

Jessica Li

How did you become interested in biology?

I've always had a baseline interest in biology. I think learning about how life works is pretty compelling in itself, and it still amazes me how elegant, efficient and overall ingenious biological processes can be. I enjoyed high school biology classes and was good at it, so I majored in biology as an undergraduate with a rough idea to pursue something medical. Things clicked more for me when I took my first physiology classes in my second year, and understanding the logical flow of various feedback pathways just made sense to me. My passion for biology really took off when I realized how much cooler animals were than humans – we can't freeze and rethaw, hibernate, or fly over the Himalayas, but animals can. There is nothing cooler to me than how animals are able to not only live but also thrive in impossible environments (or at least, impossible to me). We are so lucky for there to be so many incredible adaptations to marvel at.

Describe your scientific journey and your current research focus

I did my undergraduate degree at the University of British Columbia. For the first two and a half years of my degree, I was planning on pursuing a career in medicine or public health. That all changed when Dr Milsom delivered a guest lecture about his lab's work on bar-headed geese which annually migrated over the Himalayas. I was engrossed by the compounding challenges of needing to perform a metabolically demanding activity in an oxygen-poor environment, and fascinated by the adaptations that allowed these geese to excel. I wouldn't stop asking him questions, and later joined his lab as an Honours student were I studied seasonal effects on metabolic scaling in adult hibernators. I completed my degree in May 2020 while Vancouver was in lockdown, so I was unable to follow through with my plans of a gap year and graduate school abroad. I was convinced to expand my undergraduate project into a MSc, and I met Dr Marshall, who became my co-supervisor. We kept expanding the project and I eventually became a PhD Candidate in 2022. My current research still centres on metabolic scaling, but I additionally consider the effects of life history, development and the ability to produce body heat independently of ambient temperature (i.e. endogenous thermogenesis).

How would you explain the main findings of your paper to a member of the public?

Every living thing requires energy. The rate at which energy is produced is our metabolic rate. Because body mass is the primary factor determining metabolic rate, there is a lot of interest in the relationship between metabolic rate and body size, otherwise known as ‘metabolic scaling’. While this scaling relationship is a useful theoretical tool for many scientists, many proposed models overlook the significant portion of life that occurs before adulthood. Consequentially, we run the risk of inappropriately applying adult models to juveniles. This project sought to compile a detailed description of the developmentally linked changes in this relationship, and did so by iteratively measuring the daily changes in mass and metabolic rate in thirteen-lined ground squirrel (Ictidomys tridecemlineatus) pups at 0–30 (inclusive), 60, 90, 120 and 465 days old. Because I. tridecemlineatus pups are born very developmentally immature, we hypothesized that the energetically demanding development of many physiological processes would be reflected in their metabolic scaling. Our results support this hypothesis, and our data indicate that there are several body size and metabolic changes unique to development. Notably, we measured an impressive, transient spike in metabolic demand starting from 18–23 days old, and closely correlating to when weaning occurs. This weaning stage marks a significant step towards adulthood, from helpless pup to increasingly independent juvenile. We also found that growth rate was not uniform throughout development, roughly quadrupling from gaining 1–4 g per day at 29 days old. The mismatch in timing between the spikes in these two events indicates that the rise in metabolism is not caused by the increased growth rate, but instead must be caused by something else (possibly the development of physiological processes associated with weaning?). Overall, our findings point to three things: (1) growth and development are extremely metabolically expensive, (2) the development of physiological processes looks to be more energetically demanding than growing body mass, and (3) the observed asynchrony supports a metabolic trade-off between the two (development versus growth).

What is the hardest challenge you have faced in the course of your research and how did you overcome it?

One of the more existential challenges I've faced is getting so caught up in the details of a project that you forget how to see the forest from the trees. I'm especially prone to this happening when I'm deep in the nitty-gritty of data analysis, or when I've been working on a specific dataset for what feels like an extremely long time. Losing scope of the bigger picture gets demoralizing, and it's easy to forget how cool your questions actually are. I'm grateful for my supervisors, Dr William K. Milsom and Dr Katie E. Marshall, for being able to pull me out of these funks: we've created an environment where I can come to them with my challenges, be frustrated and blow off some steam. We can then work together to eventually come to solutions and talk about the project scope at large so I am reminded of the bigger picture and feel inspired and energized again to keep things going.

What's next for you?

Pursuing research has taught me a lot about myself in terms of perseverance, problem solving and creativity, and it has also given me the opportunity to discover another passion of mine, which is teaching. I've had so many opportunities to teach since starting graduate school: I've given guest lectures, worked as a teaching assistant and mentored undergraduates. These let me get back to basics and appreciate new layers of understanding while also facilitating my students' problem-solving skills and ‘a-ha!’ moments which I find the most rewarding. I want to make science accessible to everyone, and I'm hoping to find a lecturing position and teach early year undergraduates. I'd love to use my expertise in physiology to spread the good word about how cool biology is, and be a role model and show them there is space for them to thrive here.