I am a PhD student in the Witt Lab at the University of New Mexico using natural history collections, field biology, and computation to address the evolutionary and ecological underpinnings and consequences of range evolution of birds.


Elevational Generalism

Most Andean birds share narrow elevational ranges thought to be set by a combination of biological and environmental factors. Very few species inhabit wide elevational ranges. Those that do must compensate for large shifts in temperture, UV exposure, and the partial pressure of oxygen. Are these exceptional species physiologically adapting in the face of gene flow or are plastic and behavioral responses allowing them to persist across diverse environmental conditions and preventing them from specializing on narrower elevation zones?

We found in Gadek et al. 2017 that elevational generalists are either in the process of diversifying, expanding across the gradient, or undertaking seasonal or resource-pulse driven elevational migration, and that elevational generalism is an unstable and emphemoral condtion.

JAE Graphical Abstract

Conceptual figure published in the Journal of Animal Ecology illustrating the three main mechanisms at play in the maintenence or erosion of elevational generalist's wide ranges.

Evolution of Elevational Ranges

The evolutionary history of neotropical birds has undoubtedly been influenced by Andean uplift, leaving us with current patterns of high diversity and endemism in and around the Andes. How did modern elevational ranges form and change over time? How rapidly did they shift? And are shifts upward and downward symmetrically distributed across the elevation gradient and similarly distributed within clades. This work is being done in collaboration with Eli Stone and Selina Bauernfeind.

Downward Expansion

Figure illustrating historical dynamics of upper elevation limits. Shows rates of shift in contour crossings/10 Ma for expansions of the upper limit in green and contractions of the upper limit in purple.

Transition Between Plasticty and Adaptation During Extreme Elevational Transitions

Plastic responses to acute changes in elevation are well documented and shared across many vertebrates. Similarly, genetic adaptation to high elevation environments often acts on predictable physiological pathways. But how do these processes interact, and how do they transition between one another?

To ask these questions, we sampled the entire Peruvian range of two co-distributed marsh birds ( Phleocryptes melanops & Tachuris rubrigastra). These birds have disjunct elevational ranges, inhabiting coastal marshes at sea level and high elevation marshes above 4000 meters. Are the high elevation populations adapted(ing) to the dramatically lower oxygen availability? Or has gene flow and/or recent colonization failed to suppress short term acclimatization responses? This work is in collaboration with Jessie Williamson.

Downward Expansion

Photograph of Many-colored Rush Tyrant (Tachuris rubrigastra) from Puerto Viejo, Peru in 2016.

Malaria in Sky Islands

Avian malaria is a widspread chronic disease of birds caused by multiple Apicomplexan organisms. To understand how host and pathogen communities vary across the landscape we surveyed birds and parasite communities among Southwestern sky islands and simulated null communities to compare against empirical data.

We found that parasite communities differed between sky islands relative to null community models, suggesting idiosyncratic colonization and extirpation dynamics. This work is in collaboration with Dr. Christopher Witt, Lisa Barrow, Jessie Williamson, Selina Bauernfeind, and Rosario Marroquin-Flores.

Downward Expansion

Figure modified from Barrow et al. 2021 showing observed (dashed lines) and expected Jaccard Index values. Expected values obtained from 10,000 randomly simulated communities. Illustrates how observed communities in two "sky islands" differ from expectations.

Tracheal Evolution in Sandhill Cranes

Sandhill Cranes (Grus canadensis ) are a species among relatively few birds that exhibit tracheal elongation. Within this species there is extreme size dimorphism between subspecies. Jones & Witt 2014 found that the smaller subspecies that undertake longer distance migrations had proportionally longer trachea hypothesized to make smaller birds sound bigger. I am interested in examining the scaling relationship between tracheal elongation and body mass and the variation of sounds emitted from trachea among subspecies, age classes, and between sexes.

Downward Expansion

Preliminary figure showing the differences in the tracheal scaling relationships between greater and lesser sandhill cranes. Distributions show bootstrapped slope values for log(trachea length) ~ log(mass).

Mycobiome Characterization and Structuring Processes in Sandhill Cranes

Microbiomes are being published at a rapid pace. Yet wild bird microbiomes and specifically their fungal components (mycobiomes) are largely undescribed. Furthermore, geographic and demographic structuring effects on wild animal microbial communities remain a mystery. Baseline knowledge of the makeup of these communities and factors that affect their assembly and maintenance hold important implications for disease ecology, public health, and large scale coevolutionary processes.

We are leveraging hunter salvaged Sandhill Crane carcasses to assess fungal diversity in crane lungs and ask how the smaller more migratory subspecies differs in fungal lung diversity and abundances relative to its larger counterpart that migrates substantially shorter distances. This project is in collaboration with Paris Hamm & Michael Mann utilizing samples collected and stored in the Museum of Southwestern Biology.

Downward Expansion

Map showing drastically different breeding grounds and shared wintering grounds of lesser and greater subspecies of Sandhill Cranes across which we will test for differences in myciobiome composition.


  1. Barrow, L. N., S. M. Bauernfeind, P. A. Cruz, J. L. Williamson, D. L. Wiley, J. E. Ford, M. J. Baumann, S. S. Brady, A. N. Chavez, C. R. Gadek, S. C. Galen, A. B. Johnson, X. M. Mapel, R. A. Marroquin-Flores, T. E. Martinez, J. M. McCullough, J. McLaughlin, and C. C. Witt. 2021. Comparing community composition despite incomplete sampling and uneven abundance: a case study of sky-island haemosporidian parasites. Oecologia. In Press. https://doi.org/10.1007/s00442-021-04854-6

  2. Gadek, C. R., S. D. Newsome, E. J. Beckman, A. N. Chavez, S. C. Galen, E. Bautista & C. C. Witt. 2017. Why are tropical mountain passes “low” for some species? Genetic and stable‐isotope tests for differentiation, migration and expansion in elevational generalist songbirds. Journal of Animal Ecology, 87: 741-753. https://doi.org/10.1111/1365-2656.12779

  3. Marroquin-Flores, R. A., J. L. Williamson, A. N. Chavez, S. M. Bauernfeind, M. J. Baumann, C. R. Gadek, A. B. Johnson, J. M. McCullough, C. C. Witt, & L. N. Barrow. 2017. Diversity, abundance, and host relationships of avian malaria and related haemosporidians in New Mexico pine forests. PeerJ, 5: e3700. https://doi.org/10.7717/peerj.3700

  4. Adame, Vanesa; Chapapas, Holly; Cisneros, Marilyn; Deaton, Carol; Deichmann, Sophia; Gadek, Chauncey; Lovato, TyAnna L; Chechenova, Maria B; Guerin, Paul; Cripps, Richard M; 2016. An undergraduate laboratory class using CRISPR/Cas9 technology to mutate drosophila genes. Biochemistry and Molecular Biology Education, 44, 3: 263-275. https://doi.org/10.1002/bmb.20950


Download CV


Jessie Williamson

Jessie Williamson is an evolutionary ecologist interested in the implications of elevational migration, parasite host dynamics, and high-altitude adaptation in birds. Besides always expanding her research scope in novel ways, Jessie is a stellar field biologist and collaborator who oozes confidence under the most challenging conditions.


Emil Bautista Obispo

Emil Bautista is an expert field technician. He has undertaken dozens of expeditions with University of New Mexico, University of Alaska, and Louisiana State University among others. Emil has over 15 years of experience prepping avian round skins, taking detailed specimen data, performing physiological assays, and managing the logistics of field expeditions. He is an enthusiastic naturalist, loving father, and grandfather.


Paloma Ordoñez

Paloma Ordoñez was an amazing scientist who I was lucky enough to work with for two expeditions in 2017. Paloma passed away in 2020. I will always remeber her as an incredibly skilled field biologist, preparator, and communicator without whom I would not have been able to work many Peruvian sites. She is deeply missed within our scientific community.


Eli Stone

Eli Stone is a computer scientist and ecologist (B.S. UCLA) interested in uncovering biologically meaningful signals in phylogenies. By combining his passions of algorithms and ecology he hopes to shed new light on our understanding of the tree of life. He is an avid gardener, naturalist, and builder.


Selina Bauernfeind

Selina Bauernfeind is a computational biologist (B.S. UNM) interested in developing null models and simulations using biological data. Currently, Selina is a member of the Jacobson lab at UNM simulating biomolecular interactions using techniques from robotics, graph theory, bioinformatics, biophysics, and machine learning. Selina is an avid hiker, naturalist, and craftsperson.


Museum of Southwestern Biology

The MSB houses one of the largest natural history collections in the Southwestern United States. This massive global collection spanning 120 years has been instrumental in my training and research, allowing me to access numerous data types on thousands of species.



The Center for Ornithology and Biodiversity (CORBIDI) is a Peruvian non-profit committed to research and conservation of Peruvian fauna. They participate in massive data collection efforts on Peruvian birds and work to preserve natural history specimens. UNM's MSB has worked closely with CORBIDI's researchers in the field and on publications.