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Record: oai:ARNO:422338

AuthorsV. Merckx, P. Schols, H. Maas - Van de Kamer, P. Maas, S. Huymans, E. Smets
TitlePhylogeny and evolution of Burmanniaceae (Dioscoreales) based on nuclear and mitochondrial data
JournalAmerican Journal of Botany
Volume93
Year2006
Issue11
Pages1684-1698
ISSN0002-9122
Keywords18S rDNA; Burmanniaceae; Dioscoreales; molecular phylogeny; mycoheterotrophy; nad1 b-c intron; Thismiaceae
AbstractThe mycoheterotrophic Burmanniaceae are one of the three families currently recognized in the order Dioscoreales. Phylogenetic inference using nucleotide sequences of the nuclear 18S rDNA region and the mitochondrial nad1 b-c intron revealed two well-supported, major lineages within the family, corresponding to the two tribes recognized in the family: Burmannieae and Thismieae. All data supported a strong relationship between Thismieae and Tacca (Dioscoreaceae) making both Burmanniaceae and Dioscoreaceae polyphyletic. The three largest Burmanniaceae genera, Burmannia, Gymnosiphon, and Thismia, are paraphyletic. The splitting of Burmanniaceae into Burmannieae and Thismieae indicates two independent origins of mycoheterotrophy and correlated loss of chlorophyll in Dioscoreales. In the genus Burmannia, in which many species still contain chlorophyll, the achlorophyllous species are nested in between the autotrophic species, suggesting many independent changes from autotrophy to heterotrophy or vice versa. A Bayesian relative rates test on the 18S rDNA data showed considerable variation in substitution rates among Burmanniaceae. The substitution rates in all Thismieae and many Burmannieae are significantly faster than in Dioscoreaceae, but there seems to be no correlation between rate increases and the loss of photosynthesis.
Classification42.48
URLhttp://www.amjbot.org/content/93/11/1684.abstract
Notedoi: 10.3732/ajb.93.11.1684
Document typearticle
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