TY - JOUR
T1 - Astragalus (Fabaceae)
T2 - A molecular phylogenetic perspective
AU - Wojciechowski, Martin
N1 - Funding Information:
rum. Pages 1-229. In: V, L. Komarov, B. K, Shish-kin & E. G. Bobrov, editors. Flora of the U.S.S,R. Voh 13. Israel Program for Scientific Translations, Jerusalem, Smithsonian Institution and the National Science Foundation, Washington, D.C. Borissova, A. 1937. Genus Tragacantha Mill. Pages 479-497. In: Flora Tadzhikistanica. Voh 5. Mos-COW. Bunge, A. yon. 1868, Generis Astragali species Ger-ontogeae. Pars prior, Claves diagnosticae. M~mo-ires de F AcadEmic hnp6riale des Sciences de Saint Pdter~bourg, Septi~me S6rie, 11: 1-140. -- . 1869. Generis Astragali species Gerontogeae, Pars Altera: Specierum enumeratio. M6moires de l' Acad6mie Impdriale des Sciences de Saint P6ters-bourg, Septi6me Sdrie, 15: 1-254. Doyle, J. J., J. L. Doyle, J. A. Ballenger, E. E. Dick-son, T. Kajita & H. Ohashi. 1997. A phylogeny of the chloroplast gene rbcL in the Leguminosae: taxonomic correlations and insights into the evo-lution of nodulation. American Journal of Botany 84: 541-554. Engel, T. 1992. Petiolar anatomy of North American Astragalus species (Fabaceae) with persistent peti-oles. Aliso 13: 339-345. Felsenstein, J. 1985. Confidence limits on phyloge-nies: an approach using the bootstrap. Evolution 39: 783-791. Gillett, J. B. 1963. Astragalus L. (Leguminosae) in the highlands of tropical Africa. Kew Bulletin 17: 413-423. G6mez-Sosa, E. 1979. Las especies Sudamericanas del gEnero Astragalus (Leguminosae) I. Las espe-ties Patagdnicas Argentinas. Darwiniana 22: 313-376. -- . 1981. Novedades en el gdnero Astragalus (Le-guminosae-Galegeae). Darwiniana 23:507-516. -- . 1997. Astragalus johnstonii sp. nov. (Faba-ceae) y relaciones con el complejo A. verticillatus (Phil.) Reiche. Gayana Botfinica 54: 31-37. Goneharov, N. F., A. G. Borisova, S. G. Gorshkova, M. G. Popov & I. T. Vasil'chenko. 1965. Legu-minosae: Astragalus. Pages 1-918. ln: V. L. Ko-marov & B. K. Shishkin, editors. Flora of the U,S.SR~ Vol. 12. Israel Program for Scientific Translations, Jerusalem, Smithsonian Institution and the National Science Foundation, Washington, D.C. Gray, A. 1864. A revision and arrangement (mainly by the fruit) of the North American species of As-tragalus and Oxytropis. Proceedings of the Amer-ican Academy of Arts and Sciences 6: 188-236. Herendeen, P. S., W. L. Crepet & D. L. Diicher. 1992. The fossil history of the Leguminosae: phy-logenetic and biogeographic implications. Pages 303-316. In: R S. Herendeen & D. L. Dilcher, ed-itors. Advances in legume systematics. Part 4. The fossil record. Royal Botanic Gardens, Kew. Hu, J.-M., M. Lavin, M. F. Wojciechowski & M. J. Sanderson. 2002. Phylogenetic analysis of nuclear ribosomal ITS/5.8 S sequences in the tribe Millet-tieae (Fabaceae): Poecilanthe-Cyclolobium, the core Millettieae, and the Callerya group. System-atic Botany 27: 722-733.
Funding Information:
The author thanks R. Scherson and A. Liston for providing genomic DNAs of several South American and Asian Astragalus. The author thanks K. R Steele, A. Delgado-Salinas, and an anonymous reviewer for their many helpful comments and suggestions to improve earlier versions of this manuscript. Lastly, the author especially wishes to thank A. Liston for originally suggesting the idea of a symposium to honor the legacy of Rupert C. Barneby and his many contributions to legume systematics, and M. J. Sanderson for reinvigorating an earlier interest in this genus and for many memorable field excursions in search of the often-elusive Astragalus. This study was supported in part by funds provided by Arizona State University to the author.
PY - 2005/10
Y1 - 2005/10
N2 - Nucleotide sequences of the plastid matK gene and nuclear rDNA internal transcribed spacer region were sampled from Astragalus L. (Fabaceae), and its closest relatives within tribe Galegeae, to infer phylogenetic relationships and estimate ages of diversification. Consistent with previous studies that emphasized sampling for nrDNA ITS primarily within either New World or Old World species groups, Astragalus, with the exception of a few morphologically distinct species, is strongly supported as monophyletic based on maximum parsimony and Bayesian analyses of matK sequences as well as a combined sequence dataset. The matK data provides better resolution and stronger clade support for relationships among Astragalus and traditionally related genera than nrDNA ITS. Astragalus sensu stricto plus the genus Oxytropis are strongly supported as sister to a clade composed of strictly Old World (African, Australasian) genera such as Colutea, Sutherlandia, Lessertia, Swainsona, and Carmichaelia, plus several morphologically distinct segregates of Eurasian Astragalus. Ages of these clades and rates of nucleotide substitution estimated from a fossil-constrained, rate-smoothed, Bayesian analysis of matK sequences sampled from Hologalegina indicate Astragalus diverged from its sister group, Oxytropis, 12-16 Ma, with divergence of Neo-Astragalus beginning ca. 4.4 Ma. Estimates of absolute rates of nucleotide substitution for Astragalus and sister groups, which range from 8.9 to 10.2 × 10-10 substitutions per site per year, are not unusual when compared to those estimated for other, mainly temperate groups of papilionoid legumes. The results of previously published work and other recent developments on the phylogenetic relationships and diversification of Astragalus are reviewed.
AB - Nucleotide sequences of the plastid matK gene and nuclear rDNA internal transcribed spacer region were sampled from Astragalus L. (Fabaceae), and its closest relatives within tribe Galegeae, to infer phylogenetic relationships and estimate ages of diversification. Consistent with previous studies that emphasized sampling for nrDNA ITS primarily within either New World or Old World species groups, Astragalus, with the exception of a few morphologically distinct species, is strongly supported as monophyletic based on maximum parsimony and Bayesian analyses of matK sequences as well as a combined sequence dataset. The matK data provides better resolution and stronger clade support for relationships among Astragalus and traditionally related genera than nrDNA ITS. Astragalus sensu stricto plus the genus Oxytropis are strongly supported as sister to a clade composed of strictly Old World (African, Australasian) genera such as Colutea, Sutherlandia, Lessertia, Swainsona, and Carmichaelia, plus several morphologically distinct segregates of Eurasian Astragalus. Ages of these clades and rates of nucleotide substitution estimated from a fossil-constrained, rate-smoothed, Bayesian analysis of matK sequences sampled from Hologalegina indicate Astragalus diverged from its sister group, Oxytropis, 12-16 Ma, with divergence of Neo-Astragalus beginning ca. 4.4 Ma. Estimates of absolute rates of nucleotide substitution for Astragalus and sister groups, which range from 8.9 to 10.2 × 10-10 substitutions per site per year, are not unusual when compared to those estimated for other, mainly temperate groups of papilionoid legumes. The results of previously published work and other recent developments on the phylogenetic relationships and diversification of Astragalus are reviewed.
KW - Astragalus
KW - Diversification
KW - Fabaceae
KW - Neo-Astragalus
UR - http://www.scopus.com/inward/record.url?scp=31144468909&partnerID=8YFLogxK
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U2 - 10.1663/0007-196X(2005)057[0382:AFAMPP]2.0.CO;2
DO - 10.1663/0007-196X(2005)057[0382:AFAMPP]2.0.CO;2
M3 - Review article
AN - SCOPUS:31144468909
SN - 0007-196X
VL - 57
SP - 382
EP - 396
JO - Brittonia
JF - Brittonia
IS - 4
ER -