SLOTTA, TRACEY A. B.* AND DUNCAN M. PORTER. Biology Department, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. - Phylogenetic analysis of Iliamna (Malvaceae) using the internal transcribed spacer (ITS).
The eight species of Iliamna have a taxonomically complex
history. Since its conception in 1906, the genus was not recognized
for some time, several species were placed into other genera, and the
status of a few species was questioned. Six species are located in
western North America and two are found isolated to the east. Species
in Iliamna are very similar morphologically with only a few
characters distinguishing several as separate entities. The need for
systematic study became apparent since all but one species is
considered rare or endangered and the differentiation between two
endangered species, I. corei and I. remota, was unclear
in a previous study using RAPDs. Of the western species, four overlap
in distribution (I. crandalii, I. grandiflora, I. longisepala,
and I. rivularis) and their recognition as independent species
has been questioned. The focus of this study was to develop a
phylogeny for Iliamna using sequences from the Internal
Transcribed Spacer Region in order to determine the biogeographical
and evolutionary history. Cladistic analyses were performed and the
resulting phylogeny is presented. Iliamna forms a
well-supported clade distinct from related genera and is monophyletic.
Three well-supported groups are formed. One contains representatives
from the Pacific Northwest and forms the base of the genus. Another
contains all of the remaining species with the third clade nested
therein. This last clade contains the two eastern species, I.
corei and I. remota, but there is little to support the
divergence of these taxa as distinct species. Unfortunately, there is
not enough variability in the ITS region to separate the western
species I. crandalii, I. grandiflora, I. longisepala, and I.
rivularis as distinct species either. The ITS data does provide
information that brings new insight to the origination of the genus
and its distribution, yet further work remains to resolve the
Key words: Iliamna, internal transcribed spacer (ITS), Malvaceae, phylogeny