ECR Spotlight – Blanca Jimeno and Paola Merino Millanes Free

Blanca Jimeno and Paola Merino Millanes

How did you become interested in biology?

Paola: I have always lived close to nature, and since I was a child my family has instilled in me the importance of nature, of understanding it and taking care of it. That is why since I can remember I have wanted to understand everything that happens in it and how it works. This is what led me to become interested in biology. But it was not until the last year of my career that I discovered animal physiology, and the importance of its research.

Blanca: My interest in biology started during my very first years of life. I really enjoyed going into nature, and used to show a deep care about every single living creature (but especially animals). This naturally evolved as years passed, turning into a growing interest in how animals work and in understanding their interactions with the environment they live in. This aim to understand better how animals live and why they behave the way they do inspired me to study biology.

Describe your scientific journey and your current research focus

Blanca: Understanding the causes of the differences in organismal responses to internal and external perturbations becomes fundamental towards predicting their capacity to cope and the impact of rapid anthropogenic change on animal populations. My research develops interdisciplinary approaches to investigate physiological and molecular processes underlying organismal responses to environmental change. I combine experimental and observational studies in the field and in the lab, using birds as the main study species and merging ecophysiology, behavioural ecology and evolutionary biology.

My research trajectory has gradually evolved across complexity scales: from the descriptive study of behavioural patterns in the very first stages of my career, through endocrine dynamics and energy metabolism during my PhD, to epigenetics and transcriptomics during my postdoc years.

I am currently on my third postdoc. I am from Spain and currently based there, but during my research career I have been based in four different countries (Spain, The Netherlands, Germany and USA) and have visited many others.

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

Hormones are chemical messengers that translate environmental cues into animal behavioural or physiological responses. A specific group of hormones (glucocorticoids) are widely known as ‘stress hormones’, and thus higher levels of these hormones in the blood are often interpreted as animals (including humans) being in worse condition, or under harsh environmental conditions. Despite this widespread assumption, the causes of variation in glucocorticoid levels are not well established, and we could be misinterpreting the information they provide. It is well known that glucocorticoids have a primary role in producing and mobilizing fuel to face increased energetic demands (which occurs on a day-by-day basis and independently of whether the situation is harsh or ‘stressful’). Because sudden, unpredicted or ‘stressful’ situations will always pose an energetic challenge to animals (which will need a boost of energy reserves to face – or run from – the threat), we tested the hypothesis that glucocorticoid levels do not increase with ‘stress’ beyond the effects of this stress on energy demand. To investigate this, we compared glucocorticoid responses in free-living birds under different experimental treatments, including a temperature decrease (simulating an energetic challenge they are used to) and a standardized stressful treatment (restraint). We found that glucocorticoid responses to both treatments were similar, which points at glucocorticoid variation not differing between environmental contexts differing in nature but posing an energetic challenge. Furthermore, glucocorticoid levels and responses were comparable to those of glucose (the main fuel source in birds), further supporting the energetic nature of such responses. Our work provides support for the association between glucocorticoids and energy metabolism across environmental challenges, with both glucocorticoids and glucose reflecting the increases in energy expenditure, independently of the nature of the stimulus.

Why did you choose JEB to publish your paper?

Paola: Blanca (my supervisor and co-author) suggested JEB as the most appropriate target journal for this work, and one that would allow it to have a high visibility and impact. She had had a good previous experience with the journal and encouraged me to try it when submitting my first scientific work, as it is also a very welcoming journal for early career researchers. I agreed with her from the beginning, because knowing the journal and its reputation, I knew that it would be a place where the work would be well valued.

What do you enjoy most about research, and why?

Paola: It is difficult to choose a concrete part of the whole process, but I think what I like the most is field work, monitoring the population, as well as planning the experimental design, conducting the experiment and dealing with possible unforeseen events. I also like to do the data processing, where you can already observe certain patterns that can start giving an answer to the hypothesis.

Blanca: Doing research gives me the opportunity to pursue and satisfy my own scientific curiosity and the questions I am most interested in, which allows me to keep on learning and growing every day. Mentoring hard-working and motivated students like Paola is always a highly enriching experience, too. I also find working in the field, and being able to observe bird species closely in their environment, highly rewarding.

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

Blanca: The difficulties linked to the lack of stability that this career entails. Moving to a different place frequently (and always for temporary contracts) often challenges one's mental, social and emotional stability. To overcome that, I try to keep in mind all the good things that this career also brings and how enriching it is personally, and appreciate these things on a day-by-day (or year-to-year) basis. All in all, I feel lucky to be able to work as a scientist!

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

Paola: The most important thing I have learned in my, for now, brief career is that there can always be unforeseen events when you carry out an experiment, especially if it is done in the field. That's why you always have to have a plan B and know how to cope with the circumstances that happen to you at the time in order to be able to solve them as efficiently as possible. In addition, I have learned that even if the results do not turn out as expected, it is always a valid result that will contribute to increasing the knowledge of the area of study.

What's next for you?

Blanca: I would really like to keep on developing my research career, including additional expertise and techniques that complement the ones I already have. I aim to soon get a permanent position and establish my own lab (preferably in Spain, but who knows!), where I will keep on developing my research line that will build on interdisciplinarity, merging ecophysiology, behavioural ecology and (epi)genetics.