NEPOKROEFF, MOLLY1*, WARREN L. WAGNER2, STEVEN G. WELLER3, PAMELA S. SOLTIS4, ELIZABETH A. ZIMMER1, ANN K. SAKAI3, and DOUGLAS E. SOLTIS4. 1Laboratory of Molecular Systematics, Smithsonian Institution, Suitland, MD 20746, USA.; 2Department of Systematic Biology (Botany), Smithsonian Institution, Washington, D.C. 20560, USA.; 3Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92717, USA.; 4Florida Museum of Natural History and the Genetics Institute, University of Florida, Gainesville, FL 32611, USA.. - Diversification in the endemic Hawaiian subfam. Alsinoideae (Caryophyllaceae): evidence from nrDNA ITS, ETS sequences and morphology.
.
The endemic Hawaiian Alsinoideae genera Schiedea and
Alsinidendron (Caryophyllaceae) comprise the fifth largest
radiation of flowering plants in the Hawaiian Islands, and one of the
most diverse lineages in terms of morphology, habit, breeding system
and habitat preference. The Hawaiian Alsinoideae have served as a
model system for studying shifts from hermaphroditism to dimorphic
breeding systems (dioecy, subdioecy and gynodioecy). Because of the
possibility that habitat shifts have led to the evolution of
dimorphism, the Hawaiian Alsinoideae may provide information on causal
mechanisms underlying the evolution of sexual dimorphism. Despite the
importance of phylogenetic approaches for understanding the
relationship of habitat and breeding system evolution, recent
phylogenetic analyses have failed to identify the closest relatives of
the Hawaiian clade, confounding questions of monophyly, character
state polarization and ancestral breeding system state reconstruction.
Relationships within the Hawaiian Alsinoideae have remained
unresolved, due, in part, to low genetic divergences among closely
related species, and extremely rapid radiation following colonization
of the Hawaiian Islands. In this study, we combine three data
partitions (nr ITS and ETS sequences and morphology) for
reconstructing phylogenetic relationships using maximum parsimony and
maximum likelihood. Our results suggest 1) the Hawaiian Alsinoideae
are strongly supported as monophyletic; 2) Schiedea is
paraphyletic with Alsinidendron derived within a lineage
containing S. verticillata from Nihoa; 3) S. membranacea
and S. helleri comprise the sister clade to all other members
of the lineage in Hawaii; 4) two primarily dimorphic clades identified
in morphological analyses (adamantis and globosa clades)
form a single clade in analyses based on all three data partitions,
suggesting a single origin of dimorphic breeding systems in Hawaiian
Alsinoideae. Analyses based on nucleotide partitions alone support two
separate origins of dimorphism.
Key words: Alsinidendron , breeding systems, Caryophyllaceae, habitat shifts, Hawaiian islands, Schiedea