title: A molecular survey concerning the origin of Cyperus esculentus (Cyperaceae, Poales): two sides of the same coin (weed vs. crop).
abstract: OBJECTIVE
  Cyperus esculentus is widespread in tropical and temperate zones and is also present in cooler regions. It is used as a crop plant, but it also occurs in the wild and as a weed. As a consequence of its ecological plasticity, C. esculentus has remarkable variability, with several morphotypes. Four wild-type varieties are presently recognized, in addition to the cultivated form. This study investigates the phylogenetic position and biogeography of C. esculentus with the objective of contributing new data to increase the understanding of its evolutionary history.
  
  
  METHODS
  Genealogical relationships among genotypes were inferred by using plastid DNA haplotype and nuclear ribosomal (nr) DNA ribotype sequences for 70 specimens either collected in the field or obtained from herbaria. Statistical dispersal-vicariance (S-DIVA) and Bayesian binary method (BBM) analyses were used to reconstruct the possible ancestral ranges of C. esculentus. In order to determine the age of C. esculentus, a time-measured phylogenetic analysis was performed.
  
  
  RESULTS
  Considerable variation between the chosen nuclear and plastid markers was detected (27 ribotypes vs. six haplotypes). No geographical structure was displayed among the haplotypes, but information on the dispersal pattern may be deduced. Two types of ribotypes were detected in nrDNA, with an evident geographical segregation into an Old World group and a polymorphic New World group. Both S-DIVA and BBM analyses suggested a biogeographical history in which dispersal from the African region has been crucial in shaping the current distribution pattern of C. esculentus. The most recent common ancestor between C. esculentus races has an age of 5.1 million years (95 % highest posterior density 2.5-10.2).
  
  
  CONCLUSIONS
  The molecular analysis provides novel insights into the evolutionary history of C. esculentus. The results have various taxonomic and phylogenetic implications, including a hypothesis on the origin and phylogeography of this species, which probably originated in the late Cenozoic in Africa, and reached the Americas repeatedly, independently of Columbian exchanges.
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223-Orto Botanico, 80139 Napoli, Italy and Orto Botanico, Via Foria 223, 80139, Napoli, Italy olga.decastro@unina.it odecastr@unina.it.
authors.forename: Olga
authors.initials: O
authors.lastname: De Castro
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223-Orto Botanico, 80139 Napoli, Italy and Orto Botanico, Via Foria 223, 80139, Napoli, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Gargiulo
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223-Orto Botanico, 80139 Napoli, Italy and Orto Botanico, Via Foria 223, 80139, Napoli, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Del Guacchio
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223-Orto Botanico, 80139 Napoli, Italy and Orto Botanico, Via Foria 223, 80139, Napoli, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Caputo
authors.affiliation: Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Via Foria 223-Orto Botanico, 80139 Napoli, Italy and Orto Botanico, Via Foria 223, 80139, Napoli, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: De Luca
mesh_terms: D001483:Base Sequence; D029786:Cyperus / Q000145:classification / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D005819:Genetic Markers / Q000235:genetics; D005843:Geography; D006239:Haplotypes; D008969:Molecular Sequence Data; D010802:Phylogeny; D018087:Plastids / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D004275:DNA, Ribosomal; D005819:Genetic Markers
keywords: Chufa; Cyperaceae; Cyperus esculentus; Poales; crop; dispersal–vicariance analysis; herbarium specimens; long-distance dispersal; molecular clock; tiger nut; weed; yellow nutsedge