© 2005 Society of Systematic Biologists
Phylogeny and Biogeography of Exacum (Gentianaceae): A Disjunctive Distribution in the Indian Ocean Basin Resulted from Long Distance Dispersal and Extensive Radiation
1 Laboratory of Evolutionary Botany, Institute of Botany, University of Neuchâtel Emile-Argand 11, CH-2007, Neuchâtel, Switzerland yong-ming.yuan{at}unine.ch
2 Royal Botanic Garden Edinburgh Edinburgh EH3 5LR, Scotland, United Kingdom
3 Department of Phanerogamic Botany, Swedish Museum of Natural History S-10405, Stockholm, Sweden
4 South China Botanical Garden, Chinese Academy of Sciences Guangzhou, P.R. China
Edited by Roberta Mason-Gamer: Assiciate Editor
 |
Abstract |
|---|
Disjunctive distributions across paleotropical regions in the Indian Ocean Basin (IOB) often invoke dispersal/vicariance debates. Exacum (Gentianaceae, tribe Exaceae) species are spread around the IOB, in Africa, Madagascar, Socotra, the Arabian peninsula, Sri Lanka, India, the Himalayas, mainland Southeast Asia including southern China and Malaysia, and northern Australia. The distribution of this genus was suggested to be a typical example of vicariance resulting from the breakup of the Gondwanan supercontinent. The molecular phylogeny of Exacum is in principle congruent with morphological conclusions and shows a pattern that resembles a vicariance scenario with rapid divergence among lineages, but our molecular dating analysis demonstrates that the radiation is too recent to be associated with the Gondwanan continental breakup. We used our dating analysis to test the results of DIVA and found that the program predicted impossible vicariance events. Ancestral area reconstruction suggests that Exacum originated in Madagascar, and divergence dating suggests its origin was not before the Eocene. The Madagascan progenitor, the most recent common ancestor of Exacum, colonized Sri Lanka and southern India via long-distance dispersals. This colonizer underwent an extensive range expansion and spread to Socotra-Arabia, northern India, and mainland Southeast Asia in the northern IOB when it was warm and humid in these regions. This widespread common ancestor retreated subsequently from most parts of these regions and survived in isolation in Socotra-Arabia, southern India–Sri Lanka, and perhaps mainland Southeast Asia, possibly as a consequence of drastic climatic changes, particularly the spreading drought during the Neogene. Secondary diversification from these surviving centers and Madagascar resulted in the extant main lineages of the genus. The vicariance-like pattern shown by the phylogeny appears to have resulted from long-distance dispersals followed by extensive range expansion and subsequent fragmentation. The extant African species E. oldenlandioides is confirmed to be recently dispersed from Madagascar.
Keywords: Biogeography; DIVA; Exacum; Gentianaceae; ITS; phylogeny; trnL intron
Received January 8, 2003; Revised April 22, 2003; Accepted August 10, 2004
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  J. W. Clayton, P. S. Soltis, and D. E. Soltis Recent Long-Distance Dispersal Overshadows Ancient Biogeographical Patterns in a Pantropical Angiosperm Family (Simaroubaceae, Sapindales) Syst Biol, August 14, 2009; (2009) syp041v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Moller, M. Pfosser, C.-G. Jang, V. Mayer, A. Clark, M. L. Hollingsworth, M. H. J. Barfuss, Y.-Z. Wang, M. Kiehn, and A. Weber A preliminary phylogeny of the 'didymocarpoid Gesneriaceae' based on three molecular data sets: Incongruence with available tribal classifications Am. J. Botany, May 1, 2009; 96(5): 989 - 1010. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. K. M. Kulju, S. E. C. Sierra, S. G. A. Draisma, R. Samuel, and P. C. v. Welzen Molecular phylogeny of Macaranga, Mallotus, and related genera (Euphorbiaceae s.s.): insights from plastid and nuclear DNA sequence data Am. J. Botany, October 1, 2007; 94(10): 1726 - 1743. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Syring, K. Farrell, R. Businsky, R. Cronn, and A. Liston Widespread Genealogical Nonmonophyly in Species of Pinus Subgenus Strobus Syst Biol, April 1, 2007; 56(2): 163 - 181. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Spalik and S. R. Downie The evolutionary history of Sium sensu lato (Apiaceae): dispersal, vicariance, and domestication as inferred from ITS rDNA phylogeny Am. J. Botany, May 1, 2006; 93(5): 747 - 761. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. P. Schwarz, S. Fuller, S. M. Tierney, and S. J. B. Cooper Molecular Phylogenetics of the Exoneurine Allodapine Bees Reveal an Ancient and Puzzling Dispersal from Africa to Australia Syst Biol, February 1, 2006; 55(1): 31 - 45. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Hordijk and O. Gascuel Improving the efficiency of SPR moves in phylogenetic tree search methods based on maximum likelihood Bioinformatics, December 15, 2005; 21(24): 4338 - 4347. [Abstract] [Full Text] [PDF]
|
|