Monday, August 6, 2007 - 1:50 PMOOS 6-2: Herbivore dispersal, extinction, and diet: What happens when large herbivores enter and exit North America?
Robert S. Feranec, New York State Museum
Large mammalian herbivores can significantly impact the ecology of other mammals in particular ecosystems by creating and maintaining open habitats and competing for limited resources, for example. Over time, large herbivores have repeatedly dispersed from Eurasia into North America, spread throughout the continent, and subsequently gone extinct. It can be difficult to understand the evolutionary consequences, if any, in mammalian ecology due to large mammal dispersal and extinction without, first, examining such events within a historical framework. In North America, the Quaternary Period (1.8 Ma to present) provides an ideal time frame to examine and understand mammalian ecology before, during, and after megafaunal herbivore presence. During this period, two large herbivore taxa, mammoths and bison, separately disperse into the continent. Further, this epoch is punctuated by the loss of much of the mammalian megafauna with the end-Pleistocene extinction event. This study aims to understand (1) the effect of the dispersal of mammalian megafauna on the diets of native North American herbivorous mammals, and (2) whether surviving herbivorous mammals experienced competitive release in diet after the end‑Pleistocene extinction. Diet is examined through the analysis of stable carbon isotope values ( δ13C values) obtained from mammalian body tissues such as tooth enamel and collagen. Examination of δ13C values in herbivorous mammal tooth enamel from Florida