Washington University in St. Louis
• Origins of agriculture
• Historical ecology of North America
Bison seed dispersal and plant domestication in ancient eastern North America. Mueller is an Assistant Professor at Washington University in St. Louis, by integrating morphometric, molecular, ecological, and experimental data, Mueller studies the domestication of plants and the subsequent evolution of agrobiodiversity throughout the Holocene. Millennia before maize, beans, and tropical varieties of squash were introduced into North America from their point of origin in central Mexico, early farmers along the Mississippi and its northern tributaries were cultivating and domesticating a group of native seed crops, many of which fell out of cultivation centuries ago. The seeds and fruits of these lost crops have been recovered from archaeological sites across the Midwest, from the western front of the Appalachian Mountains to the edges of the Great Plains. Morphometric studies show that they were distinct from any of their extant relatives in ways that we would expect from domesticated annual plants. These lost crops share a distinct set of traits associated with their seed dispersal mechanism, which is common to many of our small-seeded annual crops worldwide. This project is investigating the hypothesis that the ancestors of these crops are were endozoochoric (dispersed in the dung of animals), and their earliest traits of domestication – thinner seed coats, loss of dormancy, and larger seeds – are all tied into the loss of their former dispersal mechanism in favor of dispersal by humans. We are investigating the role of American bison (Bison bison) in concentrating populations of lost crop progenitors within the tallgrass prairie in order to better understand how ancient foragers encountered and interacted with these plants. The student will participate in: 1) identification of plant specimens collected on the prairie; 2) identification of seeds recovered from bison dung samples; 3) set-up and monitoring of germination experiments with seeds recovered from bison dung, and; 4) field work in the Tallgrass Prairie Preserve, OK in early June. Field work will involve walking transects, collecting plants, dung, and soil samples, cleaning and sieving dung, and conducting controlled harvests of crop wild relatives. The student will learn basic botany, field sampling techniques, database design, and data analysis. Your time will be spent at the Missouri Botanical Garden, Washington University in St. Louis, and the Tallgrass Prairie Preserve.