Robert Cieri, PhD

NSF Postdoctoral Fellow
Department of Zoology, UBC

I am an evolutionary biologist broadly interested how animal evolution is constrained and guided by interactions with the physical world. I am currently an NSF postdoctoral fellow studying how lung structure and airflow biomechanics evolved with diving and explosive ventilation in marine mammals at the University of British Columbia with Robert Shadwick. My PhD research investigated the evolution of unidirectional pulmonary airflow patterns in monitor lizards using open source computational fluid dynamics simulations. I also used XROMM to investigate the evolution of the axial skeleton and aspiration breathing in tetrapods. In my first postdoc, I used musculoskeletal models to ask how biomechanical scaling drove locomotor innovations and adaptive evolution in Australian varanid lizards. I have a passion for integrating teaching and reasearch in organismal biology, and have a proven track record for conducting high-quality research with undergraduates. I'm also committed to increasing diversity, engagement, and inclusion in biology, and am currently working to connect marine mammal science with First Nations persons in British Columbia.

Current Projects

Fluid Dynamics of Ventilation in Whales

I’m currently using CT scans and computational fluid dynamics (CFD) to investigate how lung biomechanics evolved with the marine environment in cetaceans. Whales & dolphin lungs are not only the largest in evolutionary history (!) but are subject to two interesting biomechanical challenges: they must either resist or recover from collapse due to external pressure while diving, while also ventilating effectively during extraordinarily short surface intervals. By comparing lungs from species that dive to different depths and use different ventilatory behaviours, undergraduate students and I (undergraduates made the models in Fig 5!) are investigating how the airway trees adapted to these twin challenges. Against our expectations, our main anatomical findings are that deep-diving whales (beaked whales) have relatively wider conducting airways, while the shallow-diving, faster-ventilating animals have thinner airways and less acute branching angles. We hypothesize that the thicker airways of the deep divers store gas during diving, allowing the more vulnerable terminal airways and alveoli to collapse without bursting. The next stage is to use CFD simulations to ask how these anatomical differences affect airflow patterns. We hypothesize that the narrower airways of fast ventilators will limit turbulence by increasing wall edge effects.

Scaling of Locomotion in Varanid Lizards

Because the amount of force a muscle can produce depends on its cross-sectional area, which scales with body mass 2/3, animals should become relatively weaker at greater size. Larger mammals adjust with more erect postures, but varanid lizards keep the same sprawling posture over similar body size ranges. We built musculoskeletal models of 12 species of varanid ranging from 7g (V. brevicauda) to 37 kg Komodo dragons to investigate how lizards evolved to circumvent this biomechanical size limit. We found that varanids grow bigger than expected muscles, spread walking forces over a greater time, and changing their gait. Despite these adjustments, our MSKs predict that the relentless scaling of hip forces will make locomotion impossible for sprawling animals beyond ~ 2,000 kg.

Net-Unidirectional Pulmonary Airflow in Monitor Lizards

I am using computational fluid dynamics (CFD) to simulate patterns of airflow through the diverse lungs of monitor lizards to investigate how unidirectional pulmonary airflow evolved in reptiles and birds. Unidirectional pulmononary airflow, a condition where lung gases move in the same direction during both inspiration and expiration through most or all of the lung, was originally thought to only occur in birds, but our lab group has discovered it in crocodilians, iguanas, and monitor lizards. Our work (published in The Anatomical Record) using validated CFD simulations shows that these animals have a unique net-unidirectional pattern of pulmonary airflow - although the direction of airflow reverses in many lung chambers during the breath cycle, more air moves caudally through the cental intrapulmnary bronchus and cranially through the secondary chambers! These lungs therefore combine traits from the bird and mammal respiratory systems. Check out 3D and virtual reality figures at Sketchfab.

Axial biomechanics during walking and breathing

Ventilation and locomotion are inexorably linked in vertebrates because the axial skeleton (vertebrae, ribs, and sternum) plays a vital role in each activity. The design of the axial skeleton is a trade-off between these different roles, but because we don’t have good kinematic data during each behavior, the influence of each activity on the design of the bones and joints is unclear. This is because ribs and vertebrae during breathing and locomotion move in complex, three-dimensional patterns that are hard to measure using traditional techniques. XROMM (X-ray reconstruction of moving morphology) solves this problem by coupling x-ray videos taken from more than one angle with morphological data from computed tomography (CT) to build an exact digital replica of skeletons in motion.

Diversity of lung structure and airflow patterns in varanids

Different species of monitor lizards show an amazing amount of variation in of body size, habitat, ecological niche, and metabolic rate with a similar body plan. Their lung morphology is equally diverse, presenting an ideal system to investigate the relationship between lung design and life history traits in vertebrates. The final aspect of my dissertation work seeks to compare and contrast the pulmonary airflow patterns and lung morphologies of monitor lizards through CFD modeling of animals I collected during fieldwork in Australia.

ViRTMORPH: Using Virtual Reality to Visualize and Analyze Vertebrate Morphology

We are developeing new tools for the use of virtual reality in biology. We hosted a symposium at the 2019 ICVM (International Congress of Vertebrate Morphology) in Prague, Czechia.

Recent Publications - click image for PDF

Whale lung geometry and diving

RL Cieri, MH Tawhai, M Piscitelli-Doshkov, AW Vogl, RE Shadwick. Geometric analysis of airway trees shows that lung anatomy evolved to enable explosive ventilation and prevent barotrauma in cetaceans. BioRXiv Preprint. 2024. DOI:10.1101/2024.10.16.618729.

Coordinating the Spine and Limbs in Lizards

Coordinating limbs and spine: (Pareto-) optimal locomotion in theory, in vivo, and in robots, 2024. npj Robotics. DOI:10.1038/s44182-024-00011-2.

How do Muscle Fibres Scale in Reptiles?

Cieri RL, Dick TJM, Morris JS, Clemente CJ. Scaling of fibre area and fibre glycogen concetration in the hindlimb musculature of monitor lizards: implications for locomotor performance with increasing body size. The Journal of Experimental Biology. 2022. DOI:10.1424/keb.243380.

Modular Ventilation in Snakes

Capano JG, Boback SM, Weller HI, Cieri RL, Zwemer CF, Brainerd EL. Modular lung ventilation in Boa constrictor. The Journal of Expermental Biology. 2022. DOI:10.1242/jeb.243119.

Virtual Reality in Comparative Anatomy

Cieri RL, Turney M, ... Farmer CG. Virtual and augmented reality: new tools for visualizing, analyzing, and communicating complex morphology. The Journal of Morphology. 2021. DOI:10.1002/jmor.21421.

The scaling of Ground Reaction Forces in Monitor Lizards

Cieri RL, Irwin RJ, Rumsey D, Dick TJM, and Clemente CJ. Ground reaction forces in monitor lizards and the scaling of locomotion in sprawling tetrapods. Biology Letters. 2021. DOI:10.1098/rsbl.2020.0612.

Muscle Allometry in Varanid Limbs

Cieri RL, Dick TJM, and Clemente CJ. Monitoring muscle over three orders of magnitude: widespread positive allometry among locomotor and body support musculature in the pectoral girdle of varanid lizards (Varanidae). The Journal of Anatomy. 2020. DOI:10.1111/joa.13273.

The origin of costal ventilation

Cieri RL, Hatch SH, Capano JG, and Brainerd EL. Locomotor rib kinematics in two species of lizards and a new hypothesis for the evolution of aspiration breathing in amniotes. Scientific Reports. 2020. 10.1038/s41598-020-64140-y.

Net Unidirectional Airflow in Monitor Lungs (Varanus exanthematicus)

Cieri RL and Farmer CG. Computational Fluid Dynamics Reveals a Unique Net Unidirectional Pattern of Pulmonary Airflow in the Savannah Monitor Lizard (Varanus exanthematicus). The Anatomical Record. 2019. DOI:10.1002/ar.242939.

Breathing with floating ribs

Cieri RL, Moritz S, Capano JG, Brainerd EL. Breathing with floating ribs: XROMM analysis of lung ventilation in savannah monitor lizards. J Exp Biol [Internet]. 2018;221(22):jeb.189449. Available from: http://jeb.biologists.org/lookup/doi/10.1242/jeb.189449

Axial anatomy of monitor lizards

Cieri, RL (2018). The axial anatomy of monitor lizards (Varanidae). J. Anat. 233, 636–643.

Review: Pulmonary smooth muscle in vertebrates

Cieri, RL (2019). Pulmonary smooth muscle in vertebrates: A comparative review of structure and function. Integrative and Comparative Biology, 59, 10–28.

XROMM analysis of ventilation in tegus

Cieri, RL, Moritz, S, Capano, JG, & Brainerd, EL (2018). Breathing with floating ribs: XROMM analysis of lung ventilation in savannah monitor lizards. The Journal of Experimental Biology, 221, jeb.189449.

Review: Unidirectional Pulmonary Airflow

Cieri, RL, & Farmer, CG (2016). Unidirectional pulmonary airflow in vertebrates: a review of structure, function, and evolution. Journal of Comparative Physiology B, 186, 541–552.

Unidirectional airflow in green igugnas

Cieri, RL, Craven, BA, Schachner, ER & Farmer, CG (2014). New insight into the evolution of the vertebrate respiratory system and the discovery of unidirectional airflow in iguana lungs. Proceedings of the National Academy of Sciences of the United States of America, 111, 17218–17223..

Unidirectional airflow in monitors

Schachner, ER, Cieri, RL, Butler, JP & Farmer, CG (2013). Unidirectional pulmonary airflow patterns in the savannah monitor lizard. Nature, 506, 367–370.

Human self domestication in the fossil record

Cieri, RL, Churchill, SE, Franciscus, RG, Tan, J & Hare, B (2014). Craniofacial Feminization, Social Tolerance, and the Origins of Behavioral Modernity. Current Anthropology, 55, 419–443.

Teaching, Outreach, and Engagement

Traveling Tactile Toolboxes

As part of the Farmer Lab's broadening participation work, we've created traveling tactile teaching toolboxes to bring evolutionary biology to blind students.

Animated Breathing Poster

I worked with Brian Russo (www.yogabunny.com) to make an animated poster on how different animals breathe and how airflow patterns might have evolved. Click for the full version!.

NSF GK-12 Fellowship

My first year of gradute school, I served as the primary science teacher for a 4th and 5th grade classroom at Hawthorne Elementary as a TGLL (Think Globally Learn Locally) GK-12 fellow. I learned a lot about communicating science and teaching to students of all ages!

Computational Paleophysiology

Over the years I have contributed to the Computational Paleophysiology course as a teaching assistant, instructor, and curriculum designer.

BiOS CFD Video Tutorials

To faciliate more open-source computational fluid dynamics work in biology, I have set up a set of youtube tutorials about CFD modelling in OpenFOAM.

Clean the Darn Air! Ballot Initiative

I am the co-founder of a grass-roots Utah political organization that worked to get a Carbon Tax Ballot Iniative on the 2020 ballot to raise money to address local air quality problems and rural economic development.

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