CROSS, HUGH B.* AND TIMOTHY J. MOTLEY. The Lewis B. and Dorothy Cullman Molecular Systematics Program, The New York Botanical Garden, Bronx, New York 10458. And Center for Environmental Research and Conservation, Columbia University, New York, New York 10027. - Molecular systematics of Hawaiian Peperomia.
Peperomia is a large pantropical genus of more than 1000
species. The genus is represented by 25 species in Hawaii, of which
22 are endemic. A previous study of Hawaiian Peperomia
hypothesized that the present distribution of species is the result of
three or four independent colonization events to the archipelago. Many
morphological characters used for delineation of the species are
quantitative, and therefore it has been difficult to determine
relationships among Peperomia species based solely upon the
morphology. Nucleotide sequence data from the nuclear ribosomal ITS
and 5S-NTS loci were obtained from Hawaiian Peperomia as well
as from several Pacific and South America species. Cladistic analyses
of the molecular data indicate that: (1) the Hawaiian Peperomia
are of pacific ancestry and originally colonized the older
northwestern islands, and (2) the Hawaiian species form a monophyletic
group. Species relationships are still not well resolved among the
Hawaiian Peperomia, which may be the result of past and present
hybridization events. However, this study was able to resolve some
general patterns, but further research incorporating more variable
molecular data will be required to completely resolve the phylogenetic
relationships among the Hawaiian taxa.
Key words: biogeography, Hawaiian islands, hybridization, molecular, Peperomia, systematics