1LI, JIANHUA*, 2DAVID E. BOUFFORD, AND 2MICHAEL J. DONOGHUE. 1Arnold Arboretum of Harvard University, 125 Arborway, Jamaica Plain, MA 02130; 2Harvard University Herbaria, 22 Divinity Avenue, Cambridge, MA 02138. - Phylogenetics of Buckleya (Santalaceae) based on ITS sequences of nuclear ribosomal DNA.
Buckleya Torr. (Santalaceae) is a hemi-parasitic shrubby genus
with two species in China, on in Japan, and one in the sourheastern
United States. Phylogenetic relationships among these species are
controversial and have not been tested using molecular data. In this
study we used sequences of the internal transcribed spacer region of
nuclear ribosomal DNA to test previous phylogenetic hypotheses. Two
sister species pairs are well supported: B. distichophylla plus
B. graebneriana, and B. lanceolata plus B.
henryi. Sequence differences and morphological characters support
the recognition of B. lanceolata and B. henryi.
Sequence divergence between B. distichophylla and B.
graebneriana is twice as high as that between B. lanceolata
and B. henryi. These results are most consistent with the
treatment proposed by Carvell and Eshbaugh (1982). Biogeographically,
one of the Chinese species (B. graebneriana) is most closely
related to the eastern North American species (B.
distichophylla), while the other Chinese spcies (B. henryi)
is allied with the Japanese species (B. lanceolata). Maximum
likelihood analyses do not reject clock-like evolution of nrDNA ITS
spacers in Buckleya, and divergence times may date to the Late
Miocene and Pliocene.
Key words: Biogeography, Buckleya, ITS, Phylogeny, Santalaceae