HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplementary Data Submit a response View responses Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Renner, S. S. Articles by Murata, J. Search for Related Content PubMed Articles by Renner, S. S. Articles by Murata, J. Agricola Articles by Renner, S. S. Articles by Murata, J.

A chloroplast phylogeny of Arisaema (Araceae) illustrates Tertiary floristic links between Asia, North America, and East Africa¹

²Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 63121 USA; The Missouri Botanical Garden,St. Louis, Missouri 63166 USA; ³Botanical Gardens, The University of Tokyo, Tokyo 112-0001 Japan

The evolution of Arisaema is reconstructed, based on combined sequences (2048 aligned bases) from the chloroplast trnL intron, trnL-trnF spacer, and rpl20-rps12 spacer obtained for species from all 11 sections, including sectional type species and geographically disjunct East African and North American/Mexican species. Analyses were rooted with a representative sample of the closest outgroups, Pinellia and Typhonium, to rigorously test the monophyly of Arisaema. Sections in Arisaema are mostly based on leaf, stem, and inflorescence characters and, with one exception, are not rejected by the molecular data; however, statistical support for sectional relationships in the genus remains poor. Section Tortuosa, which includes eastern North American A. dracontium and Mexican A. macrospathum, is demonstrably polyphyletic. The third New World species, A. triphyllum, also occurs in eastern North America and groups with a different Asian clade than do A. dracontium/A. macrospathum. The genus thus appears to have entered North America twice. Fossil infructescences similar to those of A. triphyllum are known from approximately 18 million-year-old deposits in Washington State and can serve to calibrate a molecular clock. Constraining the age of A. triphyllum to 18 million years (my) and applying either a semiparametric or an ultrametric clock model to the combined data yields an age of approximately 31–49 my for the divergence of A. dracontium/A. macrospathum from their Asian relatives and of 19–32 my for the divergence between African A. schimperianum and a Tibetan/Nepalese relative. The genus thus provides an example of the Oligocene/Miocene floristic links between East Africa, Arabia, the Himalayan region, China, and North America. The phylogeny also suggests secondary loss of the environmental sex determination strategy that characterizes all arisaemas except for two subspecies of A. flavum, which have consistently bisexual spathes. These subspecies are tetraploid and capable of selfing, while a third subspecies of A. flavum is diploid and retains the sex-changing strategy. In the molecular trees, the sex-changing subspecies is sister to the two non-sex-changing ones, and the entire species is not basal in the genus.

Key Words: Areae • Arisaema • Beringia • biogeography • molecular clock • Pinellia • sex change • Typhonium

This article has been cited by other articles:

				L. I. Cabrera, G. A. Salazar, M. W. Chase, S. J. Mayo, J. Bogner, and P. Davila Phylogenetic relationships of aroids and duckweeds (Araceae) inferred from coding and noncoding plastid DNA Am. J. Botany, September 1, 2008; 95(9): 1153 - 1165. [Abstract] [Full Text] [PDF]

eLetters: