LATE QUATERNARY ENVIRONMENTS OF THE NORTHERN DESERTS AND CENTRAL TRANSVOLCANIC BELT OF MEXICO<sup>1</sup>

Metcalfe, Sarah E.

doi:10.3417/0026-6493(2006)93[258:lqeotn]2.0.co;2

Cited by 119 publications

(128 citation statements)

References 49 publications

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“…Our knowledge of vegetational reassortment after the ice age ended at 10,000 B.P. tells us that it probably would have taken a few thousand years for the plants to assume the elevational distributions and habitat preferences they are best adapted to now (6,42). Furthermore, we know next to nothing about how intensive human modification of landscapes during the pre-Columbian era and after may have altered the natural abundance and distribution of teosinte.…”

Section: Discussionmentioning

confidence: 99%

“…This is the period during which human populations first intensively used teosinte and turned it into maize. Cooler than present Pleistocene temperatures resulted in 800-1,200 m downward shifts of vegetation throughout Mesoamerica (6,42) and may well have caused Balsas and other teosintes (e.g., Chalco) to descend into lower lying regions and be widespread below 400-500 m above sea level, where they do not now occur. Our knowledge of vegetational reassortment after the ice age ended at 10,000 B.P.…”

Section: Discussionmentioning

confidence: 99%

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Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

Holst

Moreno

Piperno

2007

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

125

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We examined pollen grains and starch granules from a large number of modern populations of teosinte (wild Zea spp.), maize (Zea mays L.), and closely related grasses in the genus Tripsacum to assess their strengths and weaknesses in studying the origins and early dispersals of maize in its Mesoamerican cradle of origin. We report new diagnostic criteria and question the accuracy of others used previously by investigators to identify ancient maize where its wild ancestor, teosinte, is native. Pollen grains from teosinte overlap in size with those of maize to a much greater degree than previously reported, making the differentiation of wild and domesticated maize in palynological studies difficult. There is presently no valid method for separating maize and teosinte pollen on a morphological basis. Starch grain analysis, a recently developed tool of archaeobotany, appears to be of significant utility in distinguishing the seeds of teosinte from maize. We propose that the differences in starch grain morphology and size between wild and domesticated maize defined in this study may be associated with domestication genes in Zea that have been documented in the starch biosynthesis pathway. As previously reported, phytoliths effectively discriminate the female reproductive structures of Tripsacum, teosinte, and maize. Multiproxy microfossil studies of archaeological and paleoecological contexts appear to be effective tools for investigating the earliest stages of maize domestication and dispersals.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

Holst

Moreno

Piperno

2007

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

125

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“…Second, the early domesticate may have spread from the lowlands to the highlands, with a subsequent diffusion of highland maize replacing lowland populations (11). Neither resolution is particularly satisfying: parviglumis probably grew at lower altitudes during the cooler and dryer climatic conditions that likely existed around the time of maize domestication (7,12,13), and the replacement hypothesis seems unlikely given the difference in ecological adaptation between highland and lowland maize (14).…”

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.

370

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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“…Estas condiciones también han sido documentadas en los registros paleopedológicos del Nevado de Toluca (Sedov et al, 2001), el mismo Glacis de Buenavista , Teotihuacan (SolleiroRebolledo et al, 2006), Tlaxcala (Sedov et al, 2009) y Tepexpan (Sedov et al, 2010). Por su parte, Metcalfe (2006) señala que el nivel del agua en el lago de Pátzcuaro era más alto que el actual, lo que refleja condiciones más húmedas. Esta humedad se asocia con una contribución de lluvias procedentes del Pacífico durante el invierno, debido a la localización más al sur de la Zona de Convergencia Intertropical.…”

Section: Discussionunclassified

Paleosuelos y tepetates del Glacis de Buenavista Morelos (México): testigos de eventos climáticos de la transición Pleistoceno-Holoceno

Díaz‐Ortega

Solleiro‐Rebolledo

Sedov

et al. 2010

BSGM

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ResumenLa comprensión de los registros paleoclimáticos de finales del Pleistoceno, y en particular de la transición al Holoceno, es fundamental para el entendimiento del clima moderno. De este lapso, destaca el periodo Dryas Reciente (Younger Dryas), que representa una de las transiciones climáticas más dramáticas de la historia geológica reciente. Los registros paleoclimáticos en el interior del continente relacionados con este periodo se consideran de gran importancia para deducir la respuesta de los geosistemas a los cambios bruscos: deterioro del clima y su recuperación rápida. En este trabajo se presentan las evidencias paleopedológicas encontradas en el Glacis de Buenavista, Morelos, que ejemplifican las tendencias de cambio ambiental ocurrido en el periodo señalado. El clima actual en la zona muestra contrastes marcados, ya que hacia el norte (altitudes entre 2000-2200 m), es cálido-húmedo, en tanto que en el sur (altitudes entre 1800 y 1600) es cálido-semiseco, por lo que la cubierta edáfica actual conforma una climo-toposecuencia, que varía de Andosoles-Luvisoles a Vertisoles. Por su parte, los paleosuelos estudiados se refieren a un Albeluvisol (Buenavista), localizado en la parte norte y a un Gleysol (Ahuatenco), en la parte central de la geoforma. Sus edades, obtenidas por AMS, son de 12160 años A.P. y 12930 años A.P. (no calibradas), respectivamente. Las propiedades que muestran estos suelos (presencia de horizonte eluvial con procesos de estagnización superficial en el Albeluvisol, la fuerte gleyzación en el Gleysol, intemperismo moderado en ambos casos) indican un ambiente de formación húmedo-templado. Consecuentemente, no reflejan la gradación climática que se observa en la actualidad. El Gleysol se encuentra intercalado en una secuencia de tepetates (materiales volcánicos endurecidos), los cuales forman un manto entre los paleosuelos pleistocénicos y los suelos holocénicos. Su presencia se asocia con condiciones de inestabilidad climática y geomorfológica, debido a la intensa actividad volcánica y eventos torrenciales de lluvia, los cuales transportan materiales volcánicos y restos de suelos hacia la parte intermedia de la geoforma. Esta inestabilidad ambiental está relacionada con el Younger Dryas.

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LATE QUATERNARY ENVIRONMENTS OF THE NORTHERN DESERTS AND CENTRAL TRANSVOLCANIC BELT OF MEXICO¹

Cited by 119 publications

References 49 publications

Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

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

Paleosuelos y tepetates del Glacis de Buenavista Morelos (México): testigos de eventos climáticos de la transición Pleistoceno-Holoceno

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LATE QUATERNARY ENVIRONMENTS OF THE NORTHERN DESERTS AND CENTRAL TRANSVOLCANIC BELT OF MEXICO1

Cited by 119 publications

References 49 publications

Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

Identification of teosinte, maize, and Tripsacum in Mesoamerica by using pollen, starch grains, and phytoliths

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

Paleosuelos y tepetates del Glacis de Buenavista Morelos (México): testigos de eventos climáticos de la transición Pleistoceno-Holoceno

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LATE QUATERNARY ENVIRONMENTS OF THE NORTHERN DESERTS AND CENTRAL TRANSVOLCANIC BELT OF MEXICO¹