|Buckler, Edward - Ed|
Submitted to: Maydica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2004
Publication Date: 2/15/2006
Citation: Buckler Iv, E.S., Goodman, M.M., Holtsford, T.P., Doebley, J.F., G, J.S. 2006. Phylogeography of the wild subspecies of zea mays. Maydica. 51:123-134. Interpretive Summary: Although research has documented the close relationship between maize and Zea mays ssp. parviglumis and mexicana, little is known about how these populations have been shaped by the geography of Central Mexico and by the major climate changes over the last 20,000 years. We found that the current distribution of these populations is attributable to dispersal events along a specific set of paths, rather than gene flow in all directions via interbreeding. The origin of this dispersal appears to be the lowland regions of Guerrero, with movement to more highland areas brought on by the significant climatic changes of the Late Pleistocene and early Holocene. These findings are important in that they direct the focus of future germplasm surveys to include those populations with the widest range of molecular and phenotypic diversity.
Technical Abstract: Z. mays ssp. parviglumis and ssp. mexicana are the closest wild relatives to domesticated maize. Using isozyme and chloroplast evidence, this study examined how populations of these subspecies are related to one another, and how geography has structured the relationships between them. As some lines of evidence indicate that ssp. mexicana is a derived clade of ssp. parviglumis, clinal and dispersal hypotheses were tested to explain the genetic differentiation of ssp. mexicana and parviglumis populations. Simple dispersal hypotheses explained most of this genetic variation, while clinal hypotheses explained very little of the variation. The origin of this dispersal appeared to be the lowland regions of Guerrero. These dispersal events are discussed in light of Late Pleistocene and Holocene climate change and maize domestication.