Melissa Pardi has completed research for NSF EAR award number 1725154, "Clarifying Mammalian Responses To Climate Change: Improving Niche Modeling Through The Integration Of Climate And Dietary Information." During her funding period she spend two years as a postdoctoral research fellow at Vanderbilt University, Nashville, TN, working with the DeSantis DREAM (Dietary Reconstructions and Ecological Assessments of Mammals) Lab, in the department of Earth and Environmental Sciences and department of Biological Sciences.

Pardi was interested in applying multidisciplinary analytical methods to understand how climate and resource use constrain species? ecologies through time, to better understand how these phenomena impact modern animals. Two methods were applied: 1) species distribution modeling (SDM), which identifies the probability of occurrence of a species depending on available climatic variables, and 2) stable isotope analysis (SIA), which uses the isotopic chemistry of tissues (in this case, enamel) to determine the resource use of a species. These methods investigate impacts of abiotic and biotic factors on the distribution and ecology species, respectively. The aim was to combine SDM and SIA to gain new insights into ecological patterns that are not apparent when only one of these methods is applied in isolation. This work provides important insights into how the ecology and geographic distribution of species are influenced by climate and biodiversity change. These are issues of concern for modern conservation, and the fossil record provides an unparalleled opportunity to study their impacts over scales of time and space that exceed the scope of most modern ecological studies.

As a part of her professional development, Pardi was trained in several analytical techniques. She learned how to sample tooth enamel from fossil specimens, and gained valuable experience developing destructive sampling request proposals to work with museum collections. Pardi received training in the chemical preparation protocols to prepare enamel specimens for accelerator mass spectrometry. DeSantis also provided training in preparing teeth for dental microwear texture analysis (DMTA), and Pardi received training in white-light confocal microscopy and imaging software to analyze wear textures on tooth surfaces.

Pardi completed the main objectives of her research, including sampling of fossil mammal teeth for SIA, building a database of SIA for fossil mammal herbivores, and modeling the species distributions of charismatic species from the last ice age of North America, including Mammoth and Mastodon. To obtain new isotopic data, Pardi visited the National Museum of Natural History to collect samples originating from southeastern USA, and the New Mexico Museum of Natural History and Science for samples originating from the southwest. While collecting data for SIA, Pardi was also able to take high resolution molds of the teeth she sampled, which will be cast and imaged for DMTA.

Using the new stable isotope database, Pardi characterized the diets of 30 genera of North American large mammals, revealing predictable patterns of specialization and generalization across groups of taxa. The database also includes a broader global dataset of serially sampled individuals (individuals where multiple isotopic samples are taken in sequence), that were used to investigate individual dietary specialization across taxa. These dietary data were used to interpret the distribution of species over space, by analyzing the relationship between diet and environmental suitability estimated from species distribution models.

Pardi publicly disseminated her research in national and international professional venues. These included two annual meetings for the Society of Vertebrate Paleontologists in Albuquerque, NM in 2018 and Brisbane, Australia in 2019, as well as the 20^th Congress of the International Quaternary Association in Dublin, Ireland in 2019. Pardi discussed work from this fellowship during invited seminars at Austin Peay State University and Vanderbilt University. Work from this grant also supported broader impact objectives, by informing outreach to the Nashville, TN community. Pardi engaged in two science outreach events, centered on paleontology, with local Girl Scout troops to increase visibility of women in science. Pardi and DeSantis also developed an educational module "Hunger Games in the Fossil Record", through Tennessee Women In Science Engineering Technology and Research, an event held at the Adventure Science Center in Nashville, TN. This module introduces middle school and high school age students to paleoecological analyses and database resources.

Three manuscripts have been submitted for publication in peer-reviewed journals as of the end of the funding period for the fellowship. Data related to these manuscripts will available to the public in Dryad (datadryad.org) upon publication, and are being integrated into the Neotoma paleoecology database (neotomadb.org).

Last Modified: 05/24/2020
Modified by: Melissa I Pardi