Current Research Projects
Comparative phylogeography of baboons and vervets: A model for early modern human demography and biogeography
Early modern human demography and biogeography are related to a wide range of important issues in modern human origins research, from the appearance of early markers of behavioral modernity in the archaeological record to the global dispersal of Homo sapiens in the Late Pleistocene. However, our ability to discern ancient patterns of population structure from the fossil record and patterns of variation in extant populations is limited. The phylogeography of other widely-distributed, ecologically-flexible primates can provide useful insights into past human demographic and biogeographic responses to rapid climate fluctuations in the African Pleistocene. Baboons (genus Papio) and vervets (genus Chlorocebus) are broadly co-distributed with each other and human populations in woodland and savannah habitats across sub-Saharan Africa, making them good ecological model taxa for early modern human populations. This study will utilize a multi-marker approach (SNPs, skull morphology, and paleoclimate data) to assess the congruency of patterns of morphological and genetic population structure, test for concordant demographic responses to Pleistocene climate change, and identify putative glacial refugia. The results of this work will provide a model for early modern human demography and biogeography and also expand our understanding of African faunal evolution more broadly.
Past Research Projects
Paleoenvironment of Central Sumatra, Indonesia
For my undergraduate honors thesis, I participated in a multidisciplinary research project aimed at reconstructing environmental conditions on the island of Sumatra, Indonesia, at the Oligocene-Miocene boundary (~23 Ma). This study provided the first direct terrestrial evidence of the environment of Sumatra at this time period. For my research, I employed a multi-proxy approach using stable carbon isotope, geochemical, and morphological data from paleosol (ancient soil) samples from two stratigraphic sections of the Sawahlunto Formation near the Nusa Alam Lestari (NAL) coal mine west of Kandi, in west central Sumatra. I prepared paleosol samples for carbon isotopic analysis in an external lab and analyzed samples myself using Inductively-coupled Plasma Optical Emission Spectrometry (ICP-OES). The results of this analysis suggest that our study area was part of a highly productive rainforest environment in the lower reaches of a large river system. My participation in this project was supported by the Iowa Center for Research for Undergraduates Fellowship and the Ferentz Undergraduate Fellowships for Research.
Publications:
O’Shea N, EA Bettis III, Y Zaim, Y Rizal, Aswan, GF Gunnell, J-P Zonneveld, and
RL Ciochon. 2015. Paleoenvironmental conditions in the late Paleogene, Sumatra, Indonesia.
Journal of Asian Earth Sciences 111: 384-394. (PDF)
Zaim Y, Gunnell GF, Ciochon RL, Rizal Y, Aswan, and O'Shea N. 2014. Paleogene Vertebrates
from Tanahsirah, Talawi-- Ombilin Basin, West Sumatra, Indonesia: A Preliminary Field
Result. Buletin Geologi 41 (3): 175-184. (PDF)