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 during our centenary year but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Adrien A. Arias is an author on ‘ Modulation of limb mechanics in alligators moving across varying grades’, published in JEB. Adrien conducted the research described in this article while a PhD student in Dr Manny Azizi's lab at the University of California, Irvine, USA. He is now a Postdoctoral Research Fellow in the lab of Dr Nicole Danos at the University of San Diego, USA, investigating how the morphological and physiological features of vertebrate animals affect muscle–tendon function and mechanical properties.

Adrien A. Arias

Describe your scientific journey and your current research focus

I got my Bachelor of Science degree in Biology at California State University, San Bernardino (CSUSB), where I originally wanted to be a high school biology teacher. It wasn't until I joined Tomasz Owerkowicz's comparative physiology lab that I realized careers in academia were achievable by anyone with the right resources and support. As an undergrad, I worked with juvenile American alligators and was immediately drawn to the early anatomical and biomechanical studies done on this charismatic animal model (some of which were published by JEB). For my PhD, I brought the alligators to the University of California, Irvine, to work with Manny Azizi and learn techniques in muscle physiology and comparative biomechanics. My dissertation work focused on how body plan and limb posture can affect muscle–tendon mechanics, and now I plan to study how hormonal changes during pregnancy and lactation can possibly do so. I began my postdoctoral appointment with Nicole Danos at the University of San Diego in September 2023, studying the effects of pregnancy on muscle–tendon function and mechanical properties in rats.

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

Unlike most animals, alligators don't slow down when they walk uphill or downhill. They accomplish this by changing their limb movements to increase or decrease forces in the direction of travel exclusively. The sprawled limb posture of alligators also allows them to take advantage of an extra dimension of movement when walking downhill, which helps them increase stability without flexing their limbs like other legged animals do.

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?

This study shows that non-traditional animal models like alligators (and other reptiles) can offer new solutions to the challenges of legged locomotion in non-level terrain, particularly due to their limb posture. One thing I wish I had known sooner is how difficult it'd be to have alligators walk at a steady speed and step on a force plate with one limb – but no regrets!

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

The most rewarding aspect of this study was building it from the ground up and getting it published. From writing the IACUC protocol to training alligators to writing up a manuscript – they were all firsts for me so getting published (in JEB!) is so gratifying. The most challenging aspect was learning what MATLAB was and how to write a story based on messy alligator locomotion data.

Candid shot of undergrad researchers Kim Arreguin (left) and Victoria Madrid (right) helping me collect some of the data included in this paper.

Candid shot of undergrad researchers Kim Arreguin (left) and Victoria Madrid (right) helping me collect some of the data included in this paper.

Are there any important historical papers from your field that have been published in JEB? If so, which paper, and how did it pave the way for later research?

Of course, Taylor et al.'s series of papers in 1982 (beginning with ‘Energetics and mechanics of terrestrial locomotion. I. Metabolic energy consumption as a function of speed and body size in birds and mammals’; doi:10.1242/jeb.97.1.1) are iconic and set up important concepts in animal locomotion focused on linking the metabolic cost of locomotion with the mechanical energy needed to move – something we still haven't fully fleshed out. Not to mention they got O2 consumption data from 20 different mammal species for these studies (again, iconic)!

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?

Mendoza et al., 2023! (‘The effects of temperature on elastic energy storage and release in a system with a dynamic mechanical advantage latch’; doi:10.1242/jeb.245805.) I'm completely unbiased in saying this and it literally just came out, but it's such a neat study that combines innovative methods in muscle physiology to address some fundamental questions about the effects of temperature on muscle–tendon dynamics. Hopefully, it'll pave the way for more in silico muscle preparations that combine real whole-muscle data with mathematical models in real-time, because it would allow us to test hypotheses about muscle function that are impossible to test using in vitro (or in vivo) techniques alone.

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

I would like to know which animal is the most efficient at locomotion, and what physiological adaptations and/or trade-offs allow for it. Mostly because it'd give me an excuse to fly around the world and study every animal on Earth; that'd be amazing!

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?

Improving emphasis on well-being and mental health could improve a lot of ECR lives, along with systematic changes that improve salaries and other logistical issues associated with the ECR stage. While there are advisors and mentors who do so already (shout out to Tomasz, Manny and Nicole), it'd be nice to make it the norm in academia.

What's next for you?

I'll be at the University of San Diego for the next 2–3 years studying pregnant rats and broadening my toolkit as a muscle physiologist (as well as teaching Vertebrate Physiology in the spring!).

Adrien A. Arias's contact details: University of San Diego, Department of Biology, 5998 Alcalá Park, San Diego, CA 92110, USA.


A. A.
Modulation of limb mechanics in alligators moving across varying grades
J. Exp. Biol.