Dr. Catherine Badgley earned a Ph.D. in Geology from Yale in 1982 and is currently a Professor and Associate Chair for Undergraduate Studies.
My general research interest is the history of biological diversity, especially from the perspective of ancient and modern mammalian assemblages. I study change in ecological structure of mammalian faunas in relation to environmental gradients over continental regions and over geologic time. This interest links my work in paleoecology, biogeography of modern mammals, and the current loss of biodiversity. Over my academic career, my research has had four themes. The common link among these themes is the ecological and evolutionary response of biodiversity to global change. I have expertise and enduring interest in the history of life but am also interested in elucidating its relevance to contemporary environmental problems. These problems are pervasive and potentially devastating to human well-being, as well as to environmental quality and the persistence of other species. I am committed to discovering solutions to some of these problems through my research.
(1) Extracting information from the fossil record.
My early research focused on taphonomy, the study of how fossils are preserved in relation to biological and geological processes. Taphonomy is important for inferring the species richness of fossil assemblages, the relative and absolute abundances of taxa, species associations, the timing of local first and last appearances of lineages in the fossil record, and the autecology of ancient species. My work on the taphonomy of vertebrate assemblages provided paleocommunity reconstructions—corrected for taphonomic processes—for Miocene mammals of Pakistan; guidelines for estimating the number of individual animals preserved in terrestrial vertebrate fossil assemblages; and a statistical approach to evaluating real versus apparent faunal change, in light of changes in sample size for different fossilerous intervals, based on early Eocene mammalian assemblages of Wyoming. With paleomagnetist Lisa Tauxe, I wrote several papers about how time is represented in ancient sediments based on our analysis of a detailed paleomagnetic record in Miocene, fluvial sediments of Pakistan. I recently co-authored a book chapter (Blob and Badgley, in press) about quantitative approaches in taphonomy and faunal analysis of bonebeds.
(2) Ecology and evolution of mammalian faunas in response to climate.
Much of my research in the last 12 years has focused on creating large databases of modern mammalian faunas (species list of local faunas), ecological attributes of the mammalian species, and information about vegetation and climatic variables for the localities. The goal of this research is to quantify the relationship between climatic conditions and ecological properties of modern mammalian faunas, both to test hypotheses about ecological and evolutionary processes that control the composition of mammalian faunas and to provide a quantitative method of paleoclimatic inference for mammalian fossil assemblages. This work has shown that for large geographic regions (e.g., North America), environmental variables (climate and topography) predict quite well the species richness, ecological structure, and spatial turnover of mammalian assemblages.
(3) Change in the ecological diversity of mammals over time and space.
This work includes study of Miocene mammalian assemblages of the Old World, especially from a rich, well-documented record in northern Pakistan (where I have conducted field work since 1976), and a project in the formative stage to examine correlated changes in the geographic distribution of mammalian faunas and plant assemblages of North America since the last glacial maximum about 20 thousand years ago. These projects are long-term, collaborative, and interdisciplinary. The record of Miocene mammals of Pakistan allows us to evaluate faunal turnover in relation to a climatically-driven change in vegetation, from forest to grassland, that began about eight million years ago. We evaluated the dietary habits of individual animals from isotopic values (dC13, dO18) of tooth enamel and microwear of molar surfaces, as well as other aspects of dental wear and general dental morphology. Intensive isotopic sampling of herbivorous mammals from before, during, and after the vegetation change has revealed that most lineages that consumed forest vegetation (fruit, broad leaves) disappeared as forests shrank. A few lineages changed their diets to incorporate more grass and fewer broad leaves as the vegetation changed. Immigrant herbivores ate diets of mixed leaves and grass or just grass. Within two million years, three-quarters of the herbivorous lineages disappeared. This record provides detailed evidence of climatically-induced faunal change. The results of this research are relevant for understanding plant-animal interactions at the landscape scale and for conservation strategies for protecting modern biodiversity under the influence of accelerating global climate change.
(4) Agriculture and biodiversity.
Much of the impact of human activities on biodiversity today occurs directly or indirectly through agricultural practices around the world, at the scales of the field, the landscape, and the food system. Therefore, analysis of the relationship between agricultural practices and biodiversity is critical to alleviating the negative impacts of human activities. With faculty and student colleagues in the School of Natural Resources and Environment and EEB, I am evaluating the potential of more sustainable agricultural practices than the current industrial system. A paper published in 2007 demonstrates that organic agriculture has the potential to produce enough food to feed the entire human population (from the standpoint of yield). This study shows that farmers, policy makers, and consumers could plan for conversion of much more farmland to organic methods without substantially diminishing the global food supply; in developing countries, organic production could increase yields markedly.
Badgley, C., T.M. Smiley, and R. Cable. Mountains, climate, and mammals (book chapter for Mountains, Climate, and Biodiversity, C. Hoorn and A. Antonelli, eds). Wiley, in press. 2017.
Badgley, C., T.M. Smiley, E.B. Davis, L.R.G. DeSantis, D.L. Fox, S.B. Hopkins, T. Jezkova, M.D. Matocq, N. Matzke, J.L. McGuire, A. Mulch, B.R. Riddle, V.L. Roth, J.X. Samuels, C.A.E. Strömberg, R. Terry, B.J. Yanites. Biodiversity and topographic complexity: modern and geohistorical perspectives. Trends in Ecology and Evolution 32 (3): 211-226. 2017.
Domingo, S.M., L. Domingo, J. Abuela, A. Valenciano, C. Badgley, J. Morales. Feeding ecology and habitat preferences of top predators from two Miocene carnivore guilds. Paleobiology 42 (3). doi: 10.1017/pab.2015.50. 2016.
Badgley, C., Domingo, S.M., J.C. Barry, M.E. Morgan, L.J. Flynn, and D. Pilbeam. Continental gateways and the dynamics of mammalian faunas. Comptes Rendus Palevol 15: 763-779. http://dx.doi.org/10.1016/j.crpv.2015.09.004. 2015.
Smiley, T.M., J.M. Cotton, C. Badgley, and T.E. Cerling. Small-mammal isotope ecology tracks climate and vegetation gradients across western North America. Oikos, doi: 10.1111/oik.02722. 2015.