Who







I am a PhD candidate in the Witt Lab at the University of New Mexico and a wildlife biologist at Los Alamos National Laboratory. I use natural history collections, field biology, and computation to broadly address the ecological and evolutionary implications of diverse trait-environment associations.

Research

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.

Conceptual Figure

Conceptual figure 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 among 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.


Plasticity 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

The sandhill crane (Grus canadensis ) is among the few bird species that exhibit tracheal elongation. Within this species there is substantial 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 assessing the symmetry and strength of sexual dimorphism within sandhill cranes.

Downward Expansion

Posterior distributions of sexual dimorphism index for tracheal length by subspecies. Black circles, thick, and thin bars indicate the posterior median, 50, and 90 % credible intervals respectively


Evolutionary and ecological drivers of microbe-host associations in the lung mycobiomes of birds

Microbiomes are being published at a rapid pace. Yet wild bird microbiomes and specifically their fungal components (mycobiomes) are largely undescribed. Furthermore, how microbiomes are structured by phylogenetic, geographic, and life history traits remains understudied. 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 describing the first lung mycobiomes of birds and modeling the associations of phylogeny, morphology, and ecology with lung fungal communities. This project is in collaboration with Paris Hamm & Michael Mann utilizing samples collected and stored in the Museum of Southwestern Biology.

GDM

Global and subsampled generalized dissimilarity models showing geographic, morphological, and phylogenetic predictors of fungal community dissimilarity. Figure shows (height of dashed lines) that phylogenetic distance and maximum latitude of bird hosts explains the most dissimilarity among lung fungal communities

Publications


  1. Taxonomy, nomenclature, and identification of the giant hummingbirds (Patagona spp.) (Aves: Trochilidae). Williamson, JL, Gadek, CR, Gyllenhaal, EF, Bauernfeind, SM, Bautista, EO, Baumann, MJ, Ricote, N, Marra, PP, Bozinovic, F, Singh, ND, and Witt, CC. In review. Preprint

  2. Extreme elevational migration spurred cryptic speciation in giant hummingbirds. Williamson, J.L., Gyllenhaal, E.F., Bauernfeind, S.M., Bautista, E., Baumann, M.J., Gadek, C.R., Marra, P.P., Ricote, N., Valqui, T., Bozinovic, F. and Singh, N.D., 2024. Proceedings of the National Academy of Sciences, 121(21), p.e2313599121. PDF

  3. First record of Austral Negrito (Lessonia rufa) for Peru. Schmidt, CJ, Gadek, CR, Bautista, E, Segura, M, Witt, CC, 2023. Boletín UNOP Vol 18. N° 1. PDF

  4. Extraordinary levels of per- and polyfluoroalkyl substances (PFAS) in vertebrate animal tissues at a New Mexico desert oasis: multiple pathways for wildlife and human exposure. Witt, CC, CR Gadek, J-L Cartron, MJ Andersen, ML Campbell, M Castro-Farías, EF Gyllenhaal, AB Johnson, J Malaney, KN Montoya, A Patterson, NT Vinciguerra, JL Williamson, JA Cook, and JL Dunnum (2024). Environmental Research 249: 118229. PDF

  5. Intra- and interspecific nest stacking in marsh-dwelling songbirds. Gadek, C. R., Williamson, J. L., & Witt, C. C. (2022). Biotropica, 54, 1131– 1136.

  6. Blood variation implicates respiratory limits on elevational ranges of Andean birds. Ethan Linck, Jessie L. Williamson, Emil Bautista, Elizabeth J. Beckman, Phred M. Benham, Shane G. DuBay, L. Mónica Flores, Chauncey R. Gadek, Andrew B. Johnson, Matthew R. Jones, Jano Núñez-Zapata, Alessandra Quiñonez, C. Jonathan Schmitt, Dora Susanibar, Jorge Tiravanti C., Karen Verde-Guerra, Natalie A. Wright, Thomas Valqui, Jay F. Storz, and Christopher C. Witt The American Naturalist (2023) 201:5, 741-754

  7. Comparing community composition despite incomplete sampling and uneven abundance: a case study of sky-island haemosporidian parasites. 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. Oecologia. In Press.

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

  9. Diversity,abundance, and host relationships of avian malaria and related haemosporidians in New Mexico pine forests. 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. PeerJ, 5: e3700.

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

Collaborators

Jessie Williamson

Jessie Williamson is an evolutionary ecologist interested in the evolutionary and ecological 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 unstoppable field biologist and committed collaborator who oozes confidence under the most challenging conditions. Jessie is currently a NSF Postdoctoral Research Fellow and Rose Fellow at the Cornell Lab of Ornithology.

Jessie

Emil Bautista Obispo

Emil Bautista is an expert field technician. He has undertaken dozens of expeditions with the University of New Mexico, the 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.

Emil

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 remember her as an incredibly skilled field biologist, preparator, communicator, and friend . She is deeply missed within our scientific community.

Paloma

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.

Eli

Selina Bauernfeind

Selina Bauernfeind is a computational biologist (B.S. UNM) interested in developing null models and simulations using biological data. Selina earned her master's degree as a member of the Jacobson lab at UNM, simulating biomolecular interactions using techniques from robotics, graph theory, bioinformatics, biophysics, and machine learning. She now works as a computer scientist at Los Alamos National Laboratory.Selina is an relentless hiker, naturalist, and craftsperson.

Selina

Museum of Southwestern Biology

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

MSB

CORBIDI

The Center for Ornithology and Biodiversity (CORBIDI) is a Peruvian non-profit committed to research and conservation of Peruvian fauna. UNM's MSB has worked closely with CORBIDI's researchers in the field and on publications.

MSB