SMALL, RANDALL L. Department of Botany, The University of Tennessee, Knoxville TN 37996. - Phylogenetics of Hibiscus section Furcaria (Malvaceae) based on nuclear Adh and ITS sequences.
Hibiscus section Furcaria (Malvaceae) includes 100+
species distributed pantropically, with major centers of diversity in
Africa, Australia, and the New World. The section includes ten extant
diploid (n = 18) species, nine of which are primarily African, and one
New World species (H. costatus). In addition to the diploid
species there are several allopolyploid lineages ranging from
tetraploid to decaploid. Most of the extant diploid species, and
several allopolyploid species have previously been cytogenetically
characterized and placed into "genome groups" based on
chromosome pairing behavior in F1 hybrids. Despite these strong
foundational data, however, no phylogenetic studies have been
performed in this group. Accordingly, the monophyly of the diploid
genome groups and the relationships among them are currently unknown.
Further, the affiliation of two of the diploid species, H.
berberidifolius and H. costatus, are unclear. Finally, the
origins of, and relationships within and among groups of allopolyploid
species have yet to be extensively analyzed. To begin to address
these questions DNA sequence data has been generated from several
nuclear single-copy alcohol dehydrogenase (Adh) genes, as well
as from the ITS region of nuclear ribosomal DNA. Preliminary results
suggest that at least one of the genome groups may not be
monophyletic. Further, the placement of the sole New World diploid,
H. costatus, indicates that it is most closely related to the
African G-genome diploid, H. sudanensis. The relative
utilities of Adh and ITS sequences will be discussed, as will
the origins and relationships of selected allopolyploid species.
Key words: Adh, allopolyploidy, Hibiscus, ITS, Malvaceae, phylogenetics