HELFGOTT, D. MEGAN1* and BERYL B. SIMPSON2. 1Department of Biological Sciences, University of Idaho, P.O. Box 443051, Moscow, Idaho, 83844-3051; 2Section of Integrative Biology and the Plant Resources Center, The University of Texas, Austin, Texas, 78712. - Phylogenetics of Nemophila using molecular and morphological data.
The North American endemic genus Nemophila (Hydrophyllaceae)
consists of 11 species and six varieties of annual herbs found
primarily in California. Nine species occur in the western United
States as far south as Baja California, while two species (N.
phacelioides and N. aphylla) are disjunct in the
southeastern United States. The evolutionary relationships within
Nemophila remain unclear despite eight previous taxonomic
treatments and exploration of a variety of potentially useful kinds of
characters (morphology, cytology, and development). We present a
phylogenetic analysis of Nemophila and relevant taxa in the
tribe Hydrophylleae using DNA sequence data from both the nuclear
ribosomal DNA internal transcribed spacer, and from the chloroplast 3’
trnK intron. The molecular phylogenetic analyses concur with
infratribal relationships previously inferred from seed coat
characters. On our phylogeny Nemophila and Pholistoma
form an unresolved polytomy, but seed coat morphology suggests that
Pholistoma is sister to Nemophila as a whole. Within
Nemophila seven of the eight Californian species form a
strongly supported clade; the remaining taxa occur as a second, weakly
supported clade. Nonetheless, in resolved phylogenies, the two
southeastern species are never sister taxa and thus may have resulted
from independent dispersal or vicariant events. However, additional
data are needed to confirm that these species are indeed not sister
taxa.
Key words: Hydrophyllaceae, Nemophila, Pholistoma, phylogeny