ECR Spotlight – Anna Kawamoto Free

An individual Podarcis muralis undergoing an optomotor trial inside a rotating drum lined with black-and-white vertical stripes. This setup allows for estimating visual acuity by recording a reflexive tracking movement called the optomotor response.

How did you become interested in biology?

My interest in biology emerged naturally, fuelled by a fascination with living organisms, particularly those ‘non-conventional’ animals that are distant from humans in appearance and way of life. From an early age, I was captivated by the peculiar diversity of living beings and was strongly curious about animals that exhibit unusual adaptations or behaviours. I found myself particularly intrigued by species defying common expectations – whether through uncommon lifestyles, extraordinary survival strategies, intricate social interactions or peculiar colourations. Animal behaviour especially fascinated me. Mating behaviour and visual signals were particularly compelling aspects of animal communication. I was especially drawn to the striking colouration and chromatic displays that animals use to attract mates, deter rivals or convey social status. The sheer beauty and complexity of these chromatic communications inspired me and drew my attention towards ethology. This fascination deepened as I began studying ethology more formally. I became increasingly interested in how visual signals evolve, how different species perceive them, and what ecological and physiological factors influence their expression. Observing and studying these unique visual interactions gave me insights into the subtle yet powerful ways that organisms adapt, thrive and ensure their lineage persists. My passion grew steadily as I realised how much there is still to discover about the ‘colourful communication in animals’, leading me to pursue biology professionally, focusing on ethology and evolutionary ecology, with a particular emphasis on understanding the evolutionary significance behind visual communication in reptiles.

Describe your scientific journey and your current research focus

My scientific journey has been shaped by a deep curiosity for animal behaviour and an enduring fascination with visual communication in reptiles. Academically, my path began with a strong foundation in biology, biochemistry and bioinformatics at the Sorbonne University of Paris 7, France, where I developed a solid understanding of both molecular and ecological aspects of life sciences. My passion for ethology and herpetology became more defined during my master's studies in Applied Research in Ethology at the Sorbonne University of Paris 13, France, and later in Herpetology at the Vrije Universiteit Brussel, Belgium.

Yet, even before beginning my undergraduate studies, I immersed myself in various internships and training experiences related to animals, including veterinary placements, agricultural and farming experiences, and professional training in the captive management of reptiles and amphibians. These early hands-on experiences laid the groundwork for my interest in animal biology and helped me build a practical understanding of animal care and behaviour.

Through various later research internships, I explored different aspects of behavioural ecology, including the effects of environmental conditions on colour signalling in lizards and the role of UV signals in social interactions. My early work focused on understanding the honesty of ultraviolet (UV)-reflecting signals in Zootoca vivipara, which resulted in publications investigating the social costs of these signals and evolutionary significance.

As a PhD student at the University of Valencia and the Cavanilles Institute, my research focuses on the evolution of UV signals in lacertids. I am particularly interested in how these chromatic signals function in communication, their physiological and genetic underpinnings, and how they contribute to reproductive success and social dynamics. Using a multidisciplinary approach – including behavioural experiments, histology, visual modelling in visual ecology and phylogenetic analysis – I aim to uncover the selective pressures that drive the evolution of these signals.

My journey has been marked by a continuous drive to understand the complexity of visual communication in lizards and to contribute to the broader field of ethology by shedding light on how colour signals evolve and function.

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

Our study aimed to understand how well the common wall lizard (Podarcis muralis) can see fine details in its environment. Just like humans need good eyesight to read small text or recognise faces from a distance, lizards rely on their vision to find food, avoid predators and communicate.

To measure these lizards’ vision, we used two different methods. The first was a behavioural test in which we observed how the lizards reacted to stimulus patterns of black and white stripes. They would follow them with their head movements if they could see the stripes clearly. The second method involved studying their eye structure, focusing on the special cells in their retina that process visual information. Our findings showed that wall lizards do not have vision as sharp as that of humans or raptors. However, they can still see enough detail to detect other lizards from about 10 m away and distinguish small objects at close range, like insects or their colourful body markings. Their eyes are particularly adapted to spotting things on the ground, which helps them find food and stay alert to potential threats.

We also created images that simulate how these lizards might see the world. These images revealed that their colourful markings, essential for social interactions, likely work best at short distances, meaning their visual communication is most effective when they are close.

Our study helps us better understand how these lizards use their vision in everyday life. It also provides insight into how their visual abilities influence their behaviours, such as hunting, escaping predators and recognising potential mates or rivals.

Why did you choose JEB to publish your paper?

Journal of Experimental Biology (JEB) is a leading journal in comparative physiology and biomechanics, making it an ideal venue for our study on visual acuity in lizards. JEB publishes a diverse range of integrative and evolutionary research, focusing on how animals function across different levels of biological organisation. With its broad, interdisciplinary readership, the journal offers an excellent platform for disseminating our sensory biology, ethology and ecology findings. Its rigorous peer-review process and emphasis on high-quality experimental studies closely reflect our research approach.

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

One of the biggest challenges in this study was constructing the optomotor apparatus and ensuring that the printed stimuli produced accurate, artefact-free visual patterns. The ‘Effet Moiré’ was particularly problematic, as unintended interference patterns emerged when printing high spatial frequencies, biasing the responses. We had to carefully adjust the printing resolution and test different parameters to minimise these distortions. Another major challenge was identifying retinal ganglion cells (RGCs) in the histological analysis. Differentiating RGCs from displaced amacrine cells required extensive protocol optimisation and repeated validation against known morphological characteristics. Interpreting RGC distributions across whole-mount retinas while accounting for tissue shrinkage and distortions added another layer of complexity. Overcoming these obstacles required meticulous testing, consultation with experts, and combining anatomical and quantitative validation methods.

Another challenge was reconciling anatomical and behavioural estimates of visual acuity. While these approaches often align, discrepancies can arise due to methodological differences or biological factors. In our case, optomotor response (OMR) tests suggested slightly higher acuity, with almost negligible difference with anatomical RGC counts. To address this, we expanded our dataset, refined our methodology, and carefully re-examined potential artefacts influencing behavioural responses. By integrating multiple lines of evidence, we ensured a robust and transparent approach to visual acuity estimation, reinforcing the reliability of our results.

What is your favourite animal, and why?

My favourite animal is the tardigrade. I am deeply fascinated with extremophiles in general, but tardigrades are the most remarkable. These microscopic organisms can survive in the harshest conditions – extreme temperatures, radiation, the vacuum of space and even complete dehydration – by entering a state of cryptobiosis. Their resilience defies biological limits, making them a symbol of adaptability and survival. Beyond their incredible physiology, I admire tardigrades for what they represent in science. They challenge our understanding of life's boundaries and provide insights into astrobiology, evolutionary biology and potential medical applications. Their ability to endure conditions lethal to most organisms sparks curiosity about life's possibilities beyond Earth. Despite their almost indestructible nature, they are oddly endearing, with their tiny, bear-like appearance and slow, deliberate movements. Tardigrades embody the perfect blend of scientific intrigue and unexpected charm, so they remain my favourite animal.

What is the most important lesson that you have learned from your career so far?

One of the most valuable lessons I have learned is the importance of methodological consistency and transparency in comparative research. Differences in techniques can lead to inconsistencies that affect how results are interpreted, especially when comparing species with distinct visual adaptations. Ensuring methodological uniformity – or communicating variations – strengthens scientific integrity. Beyond science, I have also learned that collaboration and open discussion with peers greatly enhance research quality and innovation. Even when challenging, feedback can lead to significant improvements in methodology and interpretation.

What do you like to do in your free time?

I love to be stimulated by new experiences and challenge – not to showcase abilities, but for the joy of learning, refining skills and exploring curious new angles that can, in unexpected ways, nourish my research perspectives.

Outside research, I enjoy spending time in nature – hiking, herping or simply observing wildlife. These activities help me unwind while deepening my appreciation for animals in their environment. I am also passionate about climbing, a sport I practice at least three times a week. It requires perseverance, full-body coordination and strategic thinking – skills that, in some ways, translate into my scientific work. Cooking, particularly baking Parisian pastries, is another passion of mine. Like chemistry, it demands meticulous precision and feels deeply tied to my Parisian roots. I have also played the piano since age six, which sharpened my coordination, rhythm and ability to maintain a melody. Now, I play purely for enjoyment, interpreting pieces I love. Additionally, I have a strong appreciation for art, especially drawing realistic naturalist illustrations, and I hope to incorporate some into my work and thesis to add a personal touch. Finally, learning languages also stimulates me a lot. I speak French, English, Japanese, Italian and a little Spanish. Learning and practising all of them is a personal challenge and a way to connect with a broad range of people, shaped by my multicultural upbringing.