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. Caleb Loughran is an author on ‘ Evaporative cooling via panting and its metabolic and water balance costs for lizards in the American Southwest’, published in JEB. Caleb conducted the research described in this article while a PhD Student in Blair Wolf's lab in the Department of Biology, University of New Mexico, USA. He is now a Visiting Assistant Professor of Biology at New Mexico Highland University, USA, investigating the physiological ecology and thermal biology of reptiles, particularly with regard to how climate change will affect species distribution and persistence.

Caleb Loughran

Describe your scientific journey and your current research focus

When I went to school to study biology at Northern Arizona University, I had the opportunity to do work on reptile ecology and conservation, which included endangered garter snakes, rattlesnakes and tortoises. I was particularly fascinated with how and why there was so much herpetological diversity in the region. In thinking about how and why species were in one area but not another, I was particularly interested in understanding what features of the habitat were important to a species. As I learned more about how thermal relations with the environment influence activity, behavior and habitat use, I became interested in all the various complexities and nuances between temperature, physiology, behavior and ecology. This led to my Master's work on rattlesnake thermal ecology in Washington and my PhD work on lizard heat stress physiology in New Mexico. While much of my research is driven by exploring the mechanisms of reptile thermal physiology, the main theme I focus on is understanding how thermal relations influence physiological and ecological performance and how this can affect species distribution and persistence.

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

Just like humans sweat when it gets too hot, animals like lizards can evaporate water to cool their body temperature and avoid overheating. Lizards do this by panting, in much the same way that a dog pants. However, this comes at a cost – when a lizard pants, it loses water at a significant rate. Some of the species that are most effective at panting can lose up to 4% of the body mass per hour when they are panting at their maximum capacity! They do this by physically working to circulate air in their lungs so that they can maximize evaporation. This ability appears to be an adaptation for living in hot environments. Species that do this effectively may have the option to maintain activity during hot conditions and may have a competitive edge over species that cannot pant.

What are the potential implications of this finding for your field of research?

Lizards that are effective at panting are typically those that inhabit hotter, more arid environments. As the climate warms, species that are adapted to hot and arid environments may expand their range into areas where their ability to tolerate intense heat may allow them to outcompete species that cannot rely on thermoregulatory tools like evaporative cooling via panting. As a result, we may see species ranges expand, or contract, depending on how the temperature environment shapes thermal opportunity.

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

The searching for and the collection of the lizards was both rewarding and challenging. The species used in this study occur in a wide variety of habitats across the southwest. In searching for them in their native habitats, I was able to experience the incredible diversity of biomes that are present in the American Southwest. Also, the importance of being in these species' native habitats and observing how they used their habitats cannot be understated, as many of the ideas expressed in the article were shaped from field observations.

Why did you choose JEB to publish your paper?

JEB is an excellent journal that has a reputation of producing high quality publications that emphasize hypothesis driven questions and scientific rigor. Additionally, research that helps to understand how the interplay of physiology, behavior and ecology informs us about animal life history is supported and encouraged.

Holding a recently captured Sceloporus jarrovii in southern Arizona.

Holding a recently captured Sceloporus jarrovii in southern Arizona.

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?

JEB has a long history of publishing research on the themes of animal thermal physiology and thermoregulation. One paper that I have found particularly influential in my thinking is ‘Body weight and the energetics of temperature regulation’ by McNab (1970; doi:10.1242/jeb.53.2.329). This paper demonstrated how energetic demands can substantially vary at different life stages and has been used in discussing the metabolic theory of ecology.

Are there any modern-day 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?

A paper by Muñoz and Bodensteiner (2019) – ‘Janzen's hypothesis meets the Bogert effect: connecting climate variation, thermoregulatory behavior, and rates of physiological evolution’ (doi:10.1093/iob/oby002) – is particularly compelling because it reconciles two key concepts that are fundamental in understanding the evolutionary ecology of ectotherms. In particular, it explores how behavioral thermoregulation in ectotherms influences their evolutionary trajectory as well as limits their distribution. The conceptual synthesis in this paper will most surely have staying power.

What do you think experimental biology will look like 50 years from now?

Given the rapid decline of many species and habitats, the conservation crisis that we are facing will have to be the primary focus of experimental biology. In 50 years, I imagine that experimental biology will be applying novel techniques to try to understand how organisms are (or are not) able to adapt to the warmer and drier world. This may help us to effectively conserve (or even repatriate) many species that are particularly vulnerable to climate warming.

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

I would be most interested in comparative physiological ecology and thermal adaptation of reptile communities that occupy similar habitats but inhabit different regions of the globe. I would be most interested in asking questions that pertain convergence in physiological adaptation in individual organisms in these different regions and how these adaptations can influence community dynamics.

What's next for you?

I aim to stay in academia and work as a professor at an institution where I can establish a field-based research program that continues to explore reptile ecology and physiology. I hope to mentor students of all stages to help them build careers in wildlife research.

Caleb Loughran's contact details: New Mexico Highland University, 810 National Avenue, Las Vegas, NV 87701, USA.


C. L.
B. O.
Evaporative cooling via panting and its metabolic and water balance costs for lizards in the American Southwest
J. Exp. Biol.