ECR Spotlight – Chloe Fouilloux Free

Chloe Fouilloux

Describe your scientific journey and your current research focus

Although I am a herpetologist by training, I had originally planned to study marine biology. I wasn't very successful in this, as I attended college at the University of Minnesota, which is about as far away from a marine body of water as you can get. During my junior year, I had the luck of landing my first research assistantship with poison frogs in Guiana (with James Tumulty, now at the College of William and Mary) and I thought, ‘Well, I guess tadpoles are aquatic and that's close enough for me!’. Working with amphibians is one of the most special things I have ever done: if you stay still enough for long enough, they tend to forget about you, and you can watch animals live their lives as if no one was watching. From their territoriality to their complex parental care, it was impossible to not become completely captivated by poison frogs. After college, I explored other avenues in biology including ontogenetic adaptations of red-eyed treefrogs (with Karen Warkentin, Boston University) and the effects of habitat disturbance on diet and migration in Barbary Macaques (Fulbright Research Grant). Eventually, I found my path back to parental care and amphibians, where much to my family's confusion, I accepted a PhD position in Finland to study tropical poison frogs. Luckily, despite its geographical location, the group led by Bibiana Rojas at University of Jyväskylä (which has since migrated to the Konrad Lorenz Institute of Ethology in Vienna, Austria) provided all of the support I needed to learn about the evolutionary ecology of the dyeing poison frog, Dendrobates tinctorius. While some of my work incorporates adult behaviour by means of parental care, I primarily focus on the behaviour and risk faced by tadpoles. My current research combines field and laboratory techniques to ask questions about disease spread and decision-making in an ecological framework.

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

Poison frogs deposit their tadpoles in small pools of water formed by the vegetation (like a leaf axil), called phytotelmata. We measured the ‘turbidity’ of these pools (let's use this term for the sake of simplicity) and it turns out that the water within phytotelmata is incredibly diverse. In these systems predators can attack tadpoles from outside of pools (i.e. spiders) or can be confined within the same pools (i.e. dragonfly larvae or even cannibalistic conspecifics). How do poison frog tadpoles respond to these sources of risk, and how do their responses change when they develop in different levels of turbidity? We find that the visibility of rearing conditions affects a tadpole's perception of risk. Specifically, we find that tadpoles that develop in turbid/dark microhabitats show a much weaker response to predatory visual stimuli compared to tadpoles raised in bright/crystalline microhabitats.

What are the potential implications of this finding for your field of research, and is there anything that you learned during this study that you wish you had known sooner?

It is easy to dismiss tadpoles as a transient, rather inconsequential stage on their way their adult forms. However, tadpoles must dynamically navigate their environment by evading predators, interacting with conspecifics (who may be cannibals) and surviving harsh environmental conditions. It is surprising how little we know about their adaptations, decisions and the way that they perceive the world. We show here that tadpoles are able to identify conspecifics using only visual cues (contrary to popular belief that tadpoles aren't visually oriented) and that the environment where they develop influences the way that they interact with their environment. This has important implications for the adaptive plasticity of tadpole senses in response to their rearing conditions, and for the structuring of predator-prey interactions within communities in turbid habitats.

Which part of this research project was the most rewarding/challenging?

This paper means a lot for me because the design and execution of these experiments came from my own observations in the field. As an early career researcher, this was the first time that I was able to follow this process from start (i.e. observation, hypothesis generation) to finish (i.e. experiments and publication) which was an incredibly rewarding process. I am very thankful to my advisor, Bibiana Rojas, who whole-heartedly supported my enthusiasm and put in the time and effort to connect me with the people with the specialties we needed to refine our questions and experimental design. It is impossible to not mention that the four authors of this paper are women come from four different countries, representing both Central American and European institutions who are at diverse stages of their academic careers.

Are there any modern-day JEB papers that you think will be the classic papers of 2123? If so, which paper, and how will it pave the way for future research?

I think Dr Julie Jung's paper, ‘How do red-eyed treefrog embryos sense motion in predator attacks? Assessing the role of vestibular mechanoreception’ (doi:10.1242/jeb.206052) will become a corner stone study in phenotypic plasticity in early-stage animals. In this study, Jung et al. explore what developmental systems tadpoles use to assess risk and initiate early hatching to escape predation. It is a fantastic experimental approach to understand the plasticity of structure–function relationships and sure to become a fundamental example (although some would argue it already has!) demonstrating mechanistic research anchored in a clear evolutionary/ecological question.

If you had unlimited funding, what question in your research field would you most like to address?

Amphibians are going through their own pandemic right now. The chytrid fungus (Bd) has caused the decline of hundreds of species and the extinction of almost 100 and we still have a terrible understanding of how this disease disperses throughout the environment or how it is transmitted between animals. Part of the issue is that amphibians are so diverse in their behaviors and natural histories that it is impossible to create a one-size-fits-all approach to tracking the pathogen and limiting disease spread. If I had unlimited funding I would invest most of my energy into creating an international initiative to organize and coordinate sampling efforts of diverse amphibians on a global scale. These in situ collection efforts would be supplemented by experimental testing to simulate how pathogens spread between life stages, hijack species-specific behaviors and disperse throughout a population in a controlled environment.

What changes do you think could improve the lives of early-career researchers, and what would make you want to continue in a research career?

Great mentors! The difference between ECRs who have had supportive and engaged mentorship versus those who have not is as stark as the contrast between night and day. Scientists are busy: we are asked to teach, mentor students at various career stages, and design and implement community outreach activities while there is close to little training or guidance for any of these expectations. I think investing in training PIs (and interested PhDs/post-docs!) on how to teach and mentor, incentivizing or rewarding high-quality mentorship, and providing resources to PhD students who are struggling with work–life balance and mental health will be the foundation for the success for the future of academia.

What's next for you?

I will be starting a post-doctoral research position at the University of Wisconsin, Madison with Dr Jessica Hite, exploring disease transmission and coinfection in copepods. I am very excited to refine my empirical approaches by working with an invertebrate system and feel like I've come full-circle by finally studying a fully aquatic organism after all these years.