sunflower domestication khanal_2010

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Sunflower as a Pre-Columbian Domesticate in Mexico

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The extant cultivated sunflower, Helianthus annuus is thought to be independently domesticated in eastern North AmericaRecent archaeological evidences in Mexico urged several researchers to look for sunflower domestication in Mesoamerican regionsThe facts have been much debated

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Evidences of Mesoamerican DomesticationThree lines of evidences proposed by Lentz et al. (2008)Archaelogical dataLinguistic and ethnographic dataEthnohistorical data

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Archaelogical EvidencesSeveral wild sunflower species are native to MexicoPre-Columbian archaeological remains of wild sunflower In coprolites in Ocampo Cave, Tamaulipas, Mexico: 2900-2200 cal B.C.10 achenes from wild annuus at Tenochtitlan, Mexico

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Archaelogical EvidencesEarly domesticated sunflower remainsSan Andres site in Tabasco, MexicoAn achene (2867-2482 cal B.C.) and a seed (2875-2575 cal B.C.)

Predates all the archeological sunflower remains

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Archaelogical EvidencesCueva del Gallo, Morelos, MexicoThree large achenes (~ 290 cal B.C.)Characteristic domestication syndromes:Twist in the fruit from crowded domesticated sunflower headBiggest of all excavated sunflower achenes; outside of wild sunflower dimentions

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Mexican dissemules represent a distinct lineage from eastern North American sunflower populations

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Smiths LetterArcheological evidences for domesticated sunflower in pre-Columbian Mesoamerica are inadequateNo plant remains other than seeds and achenes

Taxonomic problems: Santa Leticia achene misclassified Insufficient morphological descriptors3 Morelos specimens may represent introduced domesticated sunflower

Despite smaller sample size, San Andres specimens represent earliest fully domesticated sunflower Paleoethnobotany is recent and/or Mexican sites are not favorableSanta Leticia is outside of wild sunflower locale PNAS reviewers scrutinized the factsMexican domestication may predate eastern North American domestication and Lentzs Reply

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Linguistic and Ethnographic DataDistinctive names and lack of phonetic resemblance to the Spanish terms suggests pre-Columbian existence

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Browns LetterLinguistic evidence is severely deficient to suggest sunflower as an pre-Columbian domesticate in Mesoamerica

Semantically transparent names are commonplaceMesoamerican names generated from ancestral languages Sunflower doesnt have one in proto-languages of earlier peroidsNo record of an word for sunflower in primitive languages of Mesoamerica

The linguistic evidence and archaeological data together demonstrate the use of domesticated sunflower in pre-Columbian times

So, what would be the cultigen called if there was no word for sunflower?and Lentzs Reply

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Ethnohistoric DataChimalacatl/chimalxochitl/chimalsuchitl represents sunflower in modern indigenous Nahua (the Aztecs) groupSpanish conquerors documented presence of sunflower in indigenous AztecsSahaguns Florentine Codex illustrates sunflower as a symbol representing shieldRulers carried jeweled sunflowers

Portrait: Netzahaulapilli, the Aztec ruler of Tetcoco

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Heiser LentzDont look like sunflowersCant be anything elseLarge receptacleLong peduncleRay and disk floretsBig flowersLabeled as chimalsuchitl

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Heisers LetterHistorical records suggesting pre-Columbian domestication of sunflower in Mesoamerica is altogether lackingSame nomenclature was used to represent more than one plant

The historical records presented are relevant

Not all drawings are from original artists Printers shared illustrationsand Lentzs Reply

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Why Mesoamerican domesticate remained so obscure?Independent Eastern North American domestication model was widely acceptedLack of archaeological evidences:Archaeologically unfavorable environment in the neotropical regionsA lag in paleoethnobotanical researchNot much exploited as North American domesticate:More a symbolic than direct feed sourcePredominance of alternative fat sources in Mesoamerican dietsNot extensively grownSpanish conquest suppressed symbolic assets of indigenous peopleMesoamerican landraces have not been scrutinized the way their North American counterparts have been

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DNA evidences: the ultimate truthTwo references to the molecular studies:

Harter AV, et al. (2004) Origin of extant domesticated sunflowers in eastern North America. Nature 430:201-205

Wills DM, Burke JM (2006) Chloroplast DNA variation confirms a single origin of domesticated sunflower (Helianthus annuus L.). J Hered 97:403-408

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Harter AV, et al. (2004) Origin of extant domesticated sunflowers in eastern North America. Nature 430:201-205Primers flanking 18 microsatellite markers spanning sunflower genome21 wild H. annuus, 8 Native American and Mexican landraces, and two elite cultivarsSTRUCTURE analysisExtant germplasm arose from wild populations in the central USA

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Wills DM, Burke JM (2006) Chloroplast DNA variation confirms a single origin of domesticated sunflower (Helianthus annuus L.). J Hered 97:403-408Primers flanking 6 polymorphic cpSSR markers26 wild H. annuus, 15 domesticated linesChloroplast haplotypes were analyzedSingle origin of the extant domesticated sunflowers outside of Mexico

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Rieseberg and Burkes Letter All available molecular data are suggestive of a single origin outside of Mexico Mexican landraces that had conspicuous uniqueness to their phenotypes shared chloroplast haplotypes of the US domesticatesBigger achenes of Mexican remains do not preclude North American dissemination

Molecular studies have not ventured Mexican domesticatesMight have hybridized with modern varieties

and Lentzs Reply

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Thank You

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BibliographyBrown CH. 2008. A Lack of Linguistic Evidence for Domesticated Sunflower in Pre-Columbian Mesoamerica. PNAS 105(30):E47Harter AV, et al. 2004. Origin of Extant Domesticated Sunflowers in Eastern North America. Nature 430:201-205.Heiser CB. 2008. How Old is the Sunflower in Mexico? PNAS 105(30):E48.Lentz DL, et al. 2001. Prehistoric Sunflower (Helianthus annuus L.) Domestication in Mexico. Econ Bot 53(3):370-376.Lentz DL, et al. 2008. Reply to Rieseberg and Burke, Heiser, Brown, and Smith: Molecular, Linguistic, and Archaelogical Evidence for Domesticated Sunflower in Pre-Columbian Mesoamerica. PNAS 105(30):E49-E40.Rieseberg L and JM Burke. 2008. Molecular Evidence and the Origin of the Domesticated Sunflower. PNAS 105(30):E46.Smith BD. 2008. Winnowing the Archaeological Evidence for Domesticated Sunflower in Pre-Columbian Mesoamerica. PNAS 105(30):E45Wills, DM and JM Burke. 2006. Chloroplast DNA Variation Confirms a Single Origin of Domesticated Sunflower (Helianthus annuus L.). J Hered 97(4):403-408.

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