MAMMOTHS, MASTODONS, AND CHRONOSPATIAL WARMING: EVOLUTIONARY ANALYSES OF PLEISTOCENE PROBOSCIDEANS FROM TEMPERATE AND TROPICAL LOCALES

Abstract

The Quaternary (the approximately the last 2.6 million years) of North America is a tremendously exciting time period to study with respect to ecology. It saw periods of immense climatic turbidity - the expansion and retreat of continental ice-sheets and large swings in temperature, resulting in the wide scale restructuring of terrestrial ecosystem. It also saw widespread migrations of many species and out of Eurasia, mostly notably of modern humans. Ancient DNA offers powerful tools to examine the relationships and responses of megafunal species to these events, but has largely focused on cold-adapted species, and within radiocarbon-time (i.e. the last 50 thousand years). In this thesis I work to expand our understanding of the genetic landscape of Pleistocene megafuna in three ways. First, I describe the analysis of coprolites from Bechan Cave, Utah and characterize the mammoth inhabitants in the broader context of North American mammoths. Second, I characterize the diversity of American mastodons across the continent and through time, showing that their range likely repeatedly expanded and contracted in response to Pleistocene glaciations. Lastly, I begin to fill in some of the gaps in the American mastodon dataset from chapter 3, and begin to address some of the taxonomic and biogeographic questions about American and Pacific mastodons in Idaho. Understanding how North American megafauna responded to these climatic and anthropogenic stresses may help to explain why so many species went extinct at the end of the last glaciation, and how species may respond to present day warming. However, it is important to include taxa from warmer locales and environments to ensure our models and hypotheses are comprehensive.