Evidence for Multiple Teosinte Hybrid Zones in Central Mexico

Abstract

1SummaryHybrid zones provide an excellent opportunity for studying population dynamics and whether hybrid genetic architectures are locally adaptive. The genus Zea contains many diverse wild taxa collectively called teosinte.Zea maysssp.parviglumis, the lowland progenitor of maize (Zea maysssp.mays), and its highland relativeZea maysssp.mexicanalive parapatrically and, while putative hybrids have been identified in regions of range overlap, these have never been deeply explored.Here we use a broadly sampled SNP data set to identify and confirm 112 hybrids betweenZea maysssp.parviglumisandZea maysssp.mexicana, mostly clustered in three genetically and geographically distinct hybrid groups in Central Mexico.These hybrid groups inhabit intermediate environments relative to parental taxa. We demonstrate that these individuals are true hybrids and not products of isolation by distance or ancestral to parviglumis and mexicana. This work expands on previous studies, clearly identifying hybrid zones inZea, genetically characterizing hybrid groups, and showing what appear to be unique genetic architectures of hybridization in distinct hybrid groups.With the potential for local adaptation, variable hybrid zone dynamics, and differential architectures of hybridization, we present these teosinte hybrids and parental taxa as a promising model system for studying hybridization and hybrid zones.