Spontaneous Hybridization between Maize and Teosinte

Ellstrand, Norman C.; Garner, Lauren C.; Hegde, S. G.; Guadagnuolo, Roberto; Blancas, Lesley

doi:10.1093/jhered/esm002

Cited by 65 publications

(51 citation statements)

References 16 publications

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“…Cultivated maize is nearly ubiquitous in Mexico and Guatemala and can be found in close proximity to all of the wild taxa of Zea. Data presented here and elsewhere (Wilkes 1977;Doebley et al 1984;Baltazar et al 2005;Fukunaga et al 2005;Ellstrand et al 2007) suggest that maize exchanges genes with its wild relatives. Broader sampling of maize and its wild relatives will be required to definitively test this hypothesis, but the possibility that domesticated maize may have functioned as a genetic go-between for wild populations certainly has profound implications both for the maintenance in situ of teosinte diversity and for our understanding of the risks and consequences of transgene escape from cultivated maize.…”

Section: Models Of Divergencesupporting

confidence: 54%

“…A potential explanation for the relatively low correlation of g between parviglumis and mexicana is that differences in population structure obscure shared history (e.g., Fukunaga et al 2005). The striking correlation of g between maize and mexicana could be indicative of recent gene flow (and thus shared history) between these taxa (Blancas et al 2002;Baltazar et al 2005;Fukunaga et al 2005;Ellstrand et al 2007); indeed, our analyses detect recent gene flow between maize and mexicana at several loci (Table 4). Pooling data across loci, our results further suggest the possibility of adaptive evolution in parviglumis.…”

Section: Discussionmentioning

confidence: 63%

“…While there is little empirical data to support a given model of speciation, previous work investigating introgression and gene flow substantiates our inferences of recent introgression. For example, hybridization is known to occur at least sporadically between domesticated maize and parviglumis (Wilkes 1977), and, despite genetic incompatibility factors limiting unidirectional gene flow between maize and mexicana (Evans and Kermicle 2001), the two taxa readily hybridize (Baltazar et al 2005;Ellstrand et al 2007). Allozyme data further suggest that introgression between maize and mexicana may be common (Blancas et al 2002), and some evidence suggests that introgression from mexicana may have contributed to maize domestication (Gallavotti et al 2004).…”

Section: Models Of Divergencementioning

confidence: 99%

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Historical Divergence and Gene Flow in the Genus Zea

2009

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Gene flow plays a fundamental role in plant evolutionary history, yet its role in population divergence-and ultimately speciation-remains poorly understood. We investigated gene flow and the modalities of divergence in the domesticate Zea mays ssp. mays and three wild Zea taxa using sequence polymorphism data from 26 nuclear loci. We described diversity across loci and assessed evidence for adaptive and purifying selection at nonsynonymous sites. For each of three divergence events in the history of these taxa, we used approximate Bayesian simulation to estimate population sizes and divergence times and explicitly compare among alternative models of divergence. Our estimates of divergence times are surprisingly consistent with previous data from other markers and suggest rapid diversification of lineages within Zea in the last $150,000 years. We found widespread evidence of historical gene flow, including evidence for divergence in the face of gene flow. We speculate that cultivated maize may serve as a bridge for gene flow among otherwise allopatric wild taxa.

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Section: Models Of Divergencesupporting

confidence: 54%

Section: Discussionmentioning

confidence: 63%

Section: Models Of Divergencementioning

confidence: 99%

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Historical Divergence and Gene Flow in the Genus Zea

2009

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“…Maize in the Mexican highlands grows sympatrically with a second subspecies of annual teosinte, Zea mays subspecies mexicana (hereafter, mexicana). Maize and mexicana are interfertile (15), and there is evidence for gene flow from mexicana into maize (5,16). Although not directly ancestral to maize, mexicana is more closely related to parviglumis than to maize (5), so gene flow from mexicana has the potential to affect the genetic similarity between highland maize populations and parviglumis.…”

mentioning

confidence: 99%

Genetic signals of origin, spread, and introgression in a large sample of maize landraces

Heerwaarden

Doebley

Briggs

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

376

354

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The last two decades have seen important advances in our knowledge of maize domestication, thanks in part to the contributions of genetic data. Genetic studies have provided firm evidence that maize was domesticated from Balsas teosinte (Zea mays subspecies parviglumis), a wild relative that is endemic to the mid-to lowland regions of southwestern Mexico. An interesting paradox remains, however: Maize cultivars that are most closely related to Balsas teosinte are found mainly in the Mexican highlands where subspecies parviglumis does not grow. Genetic data thus point to primary diffusion of domesticated maize from the highlands rather than from the region of initial domestication. Recent archeological evidence for early lowland cultivation has been consistent with the genetics of domestication, leaving the issue of the ancestral position of highland maize unresolved. We used a new SNP dataset scored in a large number of accessions of both teosinte and maize to take a second look at the geography of the earliest cultivated maize. We found that gene flow between maize and its wild relatives meaningfully impacts our inference of geographic origins. By analyzing differentiation from inferred ancestral gene frequencies, we obtained results that are fully consistent with current ecological, archeological, and genetic data concerning the geography of early maize cultivation.T he geography of origins and diversification of agricultural species has important implications for unraveling the ecological context of Neolithic societies and for understanding current patterns of diversity in domesticated plants and animals. Traditionally the realm of archeology and botany (1, 2), the study of plant domestication has seen important contributions from genetics during the last two decades (3). Genetic data often provide evidence that is hard to obtain by other means, making it an invaluable complement to other lines of inquiry.As a case in point, molecular markers were instrumental in establishing the single domestication of maize (Zea mays subspecies mays) from an extant wild relative (4, 5). Maize was shown to originate from annual teosinte (Zea mays subspecies parviglumis, hereafter parviglumis) around 9,000 y B.P., placing domestication in the mid-to lowland regions of southwest Mexico where parviglumis grows endemically. As predicted by this result (6), excavations in the heart of parviglumis' distribution have produced the earliest (8,700 y B.P.) phytolith evidence for maize cultivation (7). Other finds from Tabasco (7,300 y B.P.) (8) and Panama (7,400 y B.P.) (9) also support an early presence of maize throughout the Meso-American lowlands.Although different types of evidence seemingly concur, questions nonetheless remain about the interpretation of the genetic data. While unequivocal with respect to maize's wild ancestor, marker evidence suggests that maize from the Mexican highlands, rather than from the lowlands, is most closely related to parviglumis and appears to have given rise to all cultivars currently grown throug...

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“…Teosinte has been considered a genetic source for the improvement of agronomic characteristics of maize (Reeves 1950, Cohen and Galinat 1984, Lubberstedt et al 1998. Spontaneous hybrids have occurred between these species, allowing the transfer of genes between them (Ellstrand et al 2007). …”

Section: Introductionmentioning

confidence: 99%