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. Jeanne Brülhart is an author on ‘ Sex- and caste-specific developmental responses to juvenile hormone in an ant with maternal caste determination’, published in JEB. Jeanne conducted the research described in this article while a research assistant in Eva Schultner's lab at University of Regensburg, Regensburg, Germany. She is now a PhD student in the lab of Michel Chapuisat at University of Lausanne, Switzerland, investigating cooperation and conflicts in evolution, and their underlying proximate mechanisms.
Jeanne Brülhart
How did you become interested in biology?
As a child, I would not have imagined myself becoming a scientist. I used to spend a lot of time outside, playing with snails and ants, and was fascinated by wildlife documentaries but I had little interest for school and did not see myself going for long studies. Everything changed when I discovered biology in my first year of high school with a passionate teacher who passed on his love for the topic to me. Particularly, discovering the diversity of ways of ‘being an organism’, with often blurry limits to what counts as an individual, was completely new and mind-blowing to me. After this, it was clear that I wanted to become a biologist and I have greatly enjoyed every step of my academic journey. Today, I consider myself lucky to progress in an environment where I can continuously learn more about the amazing diversity of life.
Describe your scientific journey and your current research focus
At the end of my bachelor's at the University of Fribourg, specializing in evolutionary biology came naturally to me. First, I believe it to be the field of biology that raises some of the most profound questions, some of which with philosophical implications, but also, it connects all other fields of biology, which satisfies my broad curiosity. I did my master's at the University of Basel, working on sexual conflict in some hermaphroditic flatworms with crazy behaviors (Macrostomum flatworms), before spending some time working on short-term projects in and outside of academia to broaden my horizons. During that time, I secured funding to do a research project at the University of Regensburg to investigate the role of juvenile hormone on developmental plasticity in an ant with early caste determination (Cardiocondyla obscurior). All my research experiences have been extremely stimulating and I knew from the beginning that I wanted to continue with a PhD, I just needed to find the right position for me. After my project in Regensburg, I took one year to work at the Swiss National Science Foundation (SNSF), the main Swiss research funding agency, which allowed me to get insights into the behind the scenes of funding processes. I also used that year to acquire funding for my PhD, which I recently started at the University of Lausanne working on social evolution in the ant Formica selysi.
How would you explain the main findings/message of your paper to a member of the public?
This project investigates the mechanisms of caste determination in ants, that is the processes that decide which individuals become workers and which ones become queens. It seems that juvenile hormone (JH), a major hormone for insect development, plays an important role as it has been shown to stimulate the production of queens over workers or to give more queen-like traits to individuals, for example increased size, in several ant species.
We were interested in the ant Cardiocondyla obscurior, a species that is special in two major ways. First in addition to the two female castes (queens and workers), they produce two distinct male morphs: the most common males are small and wingless, but occasionally, larger winged males are produced. Second, it has been recently discovered that it is possible to identify the future caste of individuals already in the egg by observing crystalline deposits that build visible white shapes that form different patterns in future queens and future workers.
We treated brood of known caste with JH, its synthetic equivalent methoprene, or a control. We waited until the treated individuals became adults, and we looked at their final caste and size. We did not see any effect of the treatment on caste or morph. For females, queen-destined individuals turned into queens and worker-destined into workers. For males, only the usual wingless males were produced. For size, females were not affected by treatment as individuals treated with JH/methoprene were not different than the controls. However, treated males became larger than non-treated ones. This shows that in this species, female development is very constrained and not easy to manipulate, while males show flexibility which is more similar to results found in other ant species. In many species, workers can have an impact on caste determination, for example by feeding larvae differently to produce queens and workers. It is likely that in C. obscurior, female caste is under the sole control of queens, maybe by providing eggs with different amounts of JH.
Scanning electron microscopy (SEM) picture of a Cardiocondyla obscurior first instar larva. With their size of about half a millimetre, SEM was the only way to get a good close look at these small ants.
Scanning electron microscopy (SEM) picture of a Cardiocondyla obscurior first instar larva. With their size of about half a millimetre, SEM was the only way to get a good close look at these small ants.
What do you enjoy most about research, and why?
I particularly enjoy designing and running experiments, especially when working with animals. I love to prepare small trials to optimize the setup, find the best way to answer a research question and spend a lot of time observing the animals, which inevitably leads to new questions about aspects of their behavior or morphology. I also like when an experiment really starts. It is often very time- and energy-consuming but so satisfying to finally begin the work that has been planned so carefully. Also, knowing that all the effort will lead to data that will help answer important questions is extremely stimulating.
What is the hardest challenge you have faced in the course of your research and how did you overcome it?
The main challenge in this research project was the experimental workload and the size of the species of interest. The ant C. obscurior is tiny, and I needed to handle and treat their extremely fragile brood. It required a lot of training to be able to manipulate the brood without damage. I included several thousand individuals in my experiment, which turned into extensive delicate work. Luckily, a master's student, Anja Süss, was also involved, and with a lot of hard work and patience, we successfully completed the project.
What is the most important lesson that you have learned from your career so far?
Clearly, the most important lesson that my career brought me so far is that there is opportunity in failure. Experiments might not go as expected and careers might not follow the path that was planned, but there is always a way to turn this to one's advantage. This forces us to take new perspectives, be creative and do things that one would not have done otherwise. It leads to the development of new strengths, expertise and resilience and can make you become a better scientist and person. For example, I did not plan to wait several years between the end of my master's and the beginning of my PhD. Several of my plans were cancelled due to Covid or financial reasons and I ended up in some complicated personal situations. However, this ‘delay’ allowed me to successfully apply for funding twice, be involved in several projects that have or will lead to peer-reviewed publications, get experience outside academia, gain numerous technical skills and meet plenty of interesting people from different horizons. I believe that this non-linear career gives me a particularly strong scientific and personal background to fully profit from the opportunities to continue growing as a PhD student.
Jeanne Brülhart's contact details: University of Lausanne, 1015 Lausanne, Switzerland.
E-mail: [email protected]
