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square_tragopogon2.jpgTragopogon


The genus Tragopogon is a member of the Asteraceae (sunflower family) and contains approximately 150 species that are native to Eurasia. Interest in Tragopogon dates back to Linnaeus (1760), who first made crosses between T. pratensis and T. porrifolius. These crosses are reported to be the first ever made for scientific purposes. In more recent times, Tragopogon has been best studied in the United States, where it provides a classic example of instantaneous speciation via polyploidy (Ownbey 1950).

Tragopogon1.gif
Plate from Ownbey (1950) in which two new allopolyploid species, T. miscellus and T. mirus, were described.

Following the introduction of three diploid Tragopogon species ( T. dubius, T. pratensis, and T. porrifolius) to the northwestern United States in the early 1900s, two allopolyploid species ( T. mirus and T. miscellus) formed. The ancestries of both species have been confirmed through various molecular studies. Tragopogon dubius and T. pratensis are the diploid progenitors of T. miscellus, while T. dubius and T. porrifolius are the parents of T. mirus. Data indicate that T. miscellus and T. mirus have formed repeatedly, perhaps as many as 21 and 13 times, respectively, in the short time since the introduction of the diploid species. Tragopogon miscellus is of particular interest because it has formed reciprocally from T. dubius and T. pratensis. The reciprocally formed populations of T. miscellus differ in their inflorescence and floral morphologies: when T. dubius is the maternal progenitor, T. miscellus has long ligules and when T. pratensis is the maternal parent, the ligules are short.

Tragopogon2.gif

Studies on Tragopogon to date provide an important framework for an investigation of the genus in New Zealand, where all three diploid progenitors are known to occur. Herbarium specimen localities indicate that pairs of the diploids are likely sympatric, but whether they are hybridising and forming polyploids is not known.

People


Jennifer Tate – Genomic and transcriptomic changes in hybrids and polyploids, evolution of Tragopogon in New Zealand

Vaughan Symonds - Population genetics of the New World diploid and polyploid species, evolution of Tragopogon in New Zealand

Recent Tragopogon references


Tate, J. A., Z. Ni, A.-C. Scheen, J. Koh, C. Gilbert, Z. J. Chen, P. S. Soltis, and D. E. Soltis. 2006. Evolution and expression of homeologous loci in Tragopogon miscellus (Asteraceae), a recent and reciprocally formed allopolyploid. Genetics 173: 1599-1611. Article.

Kovaršík, A., J. C. Pires, A. R. Leitch., K. Y. Lim, A. Sherwood, R. Matyásšek, J. Rocca, D. Soltis and P. Soltis. 2005. Rapid concerted evolution of nuclear ribosomal DNA in two Tragopogon allopolyploids of recent and recurrent origin. Genetics 169: 931-944. Article.

Mavrodiev, E. V., M.Tancig, A. M. Sherwood, M. A. Gitzendanner, J. Rocca, P. S. Soltis, and D. E. Soltis. 2005. Phylogeny of Tragopogon L. (Asteraceae) based on internal and external transcribed spacer sequence data. International Journal of Plant Sciences 166: 117-133. Article.

Pires, J. C., K. Y. Lim, A. Kovaršík, R. Matyásšek, A. Boyd, A. R. Leitch, I. J. Leitch, M. D. Bennett, P. S. Soltis and D. E. Soltis. 2004. Molecular cytogenetic analysis of recently evolved Tragopogon (Asteraceae) allopolyploids reveal a karyotype that is additive of the diploid progenitors. American Journal of Botany 91: 1022-1035. Article.

Soltis, D. E., P. S. Soltis, J. C. Pires, A. Kovarik, J. A. Tate, and E. Mavrodiev. 2004. Recent and recurrent polyploidy in Tragopogon (Asteraceae): Genetic, genomic, and cytogenetic comparisons. Biological Journal of the Linnean Society 82: 485-501. Article.

Classic Tragopogon references

Linneaus, C. 1760. Disquisitio de quaestione ab Academia imperiali scientiarum Petropolitana in annum MDCCLIX pro praemio proposita: “Sexum plantarum argumentis et experimentis novis…” Academy of Sciences, St. Petersburg. Reprinted as “Disquisitio de sexu plantarum…” in Amoenitates Academicae 10:100-131 1790; in English translation as “A dissertation on the sexes of plants,” by J. E. Smith. Nichol. London. 1786.

Note: The following publications are available at JSTOR

Ownbey, M. 1950. Natural hybridization and amphiploidy in the genus Tragopogon. American Journal of Botany 37: 487-499.

Ownbey, M., and G. D. McCollum

. 1953. Cytoplasmic inheritance and reciprocal amphiploidy in Tragopogon. American Journal of Botany 40: 788-796.

Soltis, D. E., and P. S. Soltis. 1989. Allopolyploid speciation in Tragopogon: insights from chloroplast DNA. American Journal of Botany 76: 1119-1124.

Novak, S. J., D. E. Soltis and P. S. Soltis. 1991. Ownbey's Tragopogons: 40 years later. American Journal of Botany 78: 1586-1600.

Soltis, P. S., G. M. Plunkett, S. J. Novak and D. E. Soltis. 1995. Genetic variation in Tragopogon species: additional origins of the allotetraploids T. mirus and T. miscellus (Compositae). American Journal of Botany 82: 1329-1341

Other Tragopogon links

Soltis lab: University of Florida

Tragopogon project in the Soltis lab

Tragopogon treatment in the Flora of North America

Topic revision: r2 - 2010-05-27 - AndrewClarke
 
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