GENETIC AND PHENOTYPIC CONSEQUENCES OF FARMER MANAGEMENT OF FERAL Brassica rapa IN MEXICO

Abstract

Understanding the process of reciprocal genetic and cultural change involved in domestication has long been a focus of archaeology, genetics, ethnobiology, and a variety of other fields. Unfortunately, it is difficult to make inferences about the complex ecological, cultural, and evolutionary factors involved in domestication processes that happened thousands of years ago. Cases of ongoing anthropogenic selection on managed wild plants can provide unique insights into these processes. Spontaneously occurring populations of feral field mustard (Brassica rapa) in Northwest Mexico present an opportunity to understand the dynamics of human selection on wild annual plants and the dynamics involved in domestication. We collected field mustard samples from populations cultivated by Rarámuri farmers and unmanaged populations in Chihuahua, Mexico for phenotypic and population genomic analysis. We found significant differences in flowering time between managed and unmanaged populations and genetic differentiation of two managed populations from unmanaged populations in the same communities. We present rare evidence of the ongoing “redomestication” of a feral crop. This genomically-enabled short-generation plant could provide a powerful study system in the future for further understanding the ecological and cultural aspects of domestication.