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The sedgePhylogenetic, phylogeographic, and divergence time estimation analyses were carried out based on two nuclear ribosomal (ETS and ITS) regions, one nuclear single copy gene (CATP), and three plastid DNA regions (

PREMISE OF THE STUDY Barleria is a large, pantropical genus of ca. 265 species mainly distributed in the Old World with only one species, B. oenotheroides, extending to the neotropics. This amphi-Atlantic disjunction, frequently displayed by pantropical taxa, has been traditionally explained with vicariance or geodispersal hypotheses and increasingly with long-distance dispersal. The native status of this species in the New World is controversial. METHODS A molecular phylogeographic study based on the nuclear ribosomal ITS region and plastid trnL-F, rps16, and trnS-G sequences was done to clarify the origin of this tropical intercontinental disjunction. Divergence times were estimated with various analytical approaches, including different markers and primary calibration points. KEY RESULTS Divergence ages estimated for Barleria lineages disagree with vicariance or geodispersal hypotheses. Genetic differentiation of American vs. African populations of B. oenotheroides does not support a recent anthropogenic introduction to the New World. Our data suggest ancient long-distance dispersal from the Old to the New World probably during the Pliocene or Upper Miocene. The number of dispersal events remains unclear. CONCLUSIONS Our study demonstrates the native status of Barleria in the New World, resolving one of only three presumed natural Old World-New World disjunctions at the species level among Acanthaceae. This case constitutes a further documented example of the "out-of-Africa" pattern in the family, despite their lack of documented assisted-dispersal syndromes, and highlights the importance of long-distance dispersal to explain pantropical distributions in many families.

Oligomeris linifolia constitutes one of the few examples of intercontinental disjunctions at the species level between the arid regions of the Old World and SW North America. The status of the American populations has been obscure, with some authors considering the populations to be introduced, whereas others believe them to be native. To clarify these conflicting opinions, we performed phylogeographic analyses using nuclear ribosomal ITS and plastid trnL-F and rps16 sequences to infer the origin of the disjunct American populations. Two independent molecular clock approaches based on ITS and cpDNA sequences (rbcL, matK, trnL-F) were used to estimate a divergence time of O. linifolia. Low levels of sequence divergence and estimates of relatively recent splits of Oligomeris lineages disagree with the vicariance hypotheses traditionally suggested to account for New-Old World disjunctions. In addition, significant genetic differentiation of American populations does not indicate a recent anthropogenic introduction. Morphological uniformity and the sharing of haplotypes between disjunct populations, together with the molecular clock results, suggest that a long-distance dispersal event from the Old Word to SW North America may have taken place during the Quaternary, in spite of limited dispersal mechanisms in Oligomeris.