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September 1999] KRON ET AL.—PHYLOGENETICS OF ANDROMEDEAE
1295
Fig. 1. Strict consensus of all most parsimonious trees (36) from
analysis of morphological data. Length (L) 139, Consistency Index
(CI) 0.48, Retention Index (RI) 0.68. Decay values are below lines.
Taxa traditionally placed in the tribe Andromedeae are in boldface.
strongly supported by the data. Within this clade Vaccinieae
are monophyletic and form a polytomy with three
other clades. The sister relationship of Andromeda polifolia
and Zenobia pulverulenta is strongly supported by
the matK data and there is strong support for Chamaedaphne
calyculata sister to Leucothoë racemosa. These
results are different from the morphological analysis (Fig.
1) where Andromeda is indicated as more closely related
to the Lyonia group than the Gaultheria group. Similar
to the morphological analysis, Lyonia and Pieris are
monophyletic in the matK analysis. The Lyonia group
(Lyonia, Craibiodendron, Pieris, Agarista) is monophyletic
but not very strongly supported. In both the rbcL
and matK analyses the Gaultheria group is placed in the
same clade with a monophyletic Vaccinieae. In the matK
analysis this large clade is strongly supported. The results
of the rbcL analysis indicate only weak support for a
Gaultheria group Vaccinieae clade, with the clade collapsing
in trees one step longer than most parsimonious
(Fig. 3). The Gaultheria group is not supported as monophyletic
by either the rbcL or the matK analyses. Both
analyses indicate a core Gaultheria clade that includes
Tepuia, Diplycosia, Gaultheria, and Pernettya. In the
rbcL analysis Diplycosia is sister to Tepuia, whereas in
the matK analysis Diplycosia is included in a polytomy
containing Gaultheria and Pernettya. However, none of
these relationships is strongly supported in either analysis.
Combined analysis of rbcL and matK data resulted in
four most parsimonious trees (L 1495, CI 0.92, RI
0.58). The strict consensus (Fig. 5) is highly resolved
with Oxydendrum sister to the remaining ingroup taxa.
As in the separate molecular data analyses Agarista,
Lyonia, and Pieris are monophyletic, but in the combined
analysis they each have higher levels of support than in
each individual analysis. In the combined rbcL and matK
analysis Vaccinieae are monophyletic and unresolved
with respect to the Andromeda Zenobia clade and the
weakly supported clade that includes Leucothoë, Chamaedaphne,
Tepuia, Diplycosia, Gaultheria, and Pernettya.
In this analysis Gaultheria is paraphyletic with respect
to Pernettya, a relationship also found in the rbcL
and morphological analyses.
Combined molecular and morphological analysis—
This analysis resulted in the generation of a single most
parsimonious tree of 1565 steps, a consistency index (CI)
of 0.61, and a retention index (RI) of 0.59 (Fig. 6). The
position of Oxydendrum as sister to the remaining ingroup
taxa is strongly supported.
The monophyly of the Lyonia group (incl. Agarista,
Craibiodendron, Lyonia, and Pieris) is strongly supported
(d8, 99% bootstrap). Noteworthy morphological features
supportive of the monophyly of this group include
bands of fibers in the phloem (no. 1), leaves with lignified
epidermal cells (no. 13), S-shaped filaments (no. 33), and
more or less elongated testa cells (no. 57). Within this
clade, Agarista likely is sister to Pieris, and Craibiodendron
is weakly supported as the sister group of Lyonia.
Agarista, Pieris, and Lyonia are all strongly supported
as monophyletic (Fig. 6); the monophyly of Craibiodendron
was not assessed. Cladogram topology within
the Lyonia group was identical to that discovered in our
previous analysis of this group (Kron and Judd, 1997),
and that paper should be consulted for a more detailed
discussion of these generic and infrageneric relationships.
Vaccinieae form a well-supported clade (d24, 100%
bootstrap) with members of the Gaultheria group, Andromeda,
and Chamaedaphne. A significant morphological
synapomorphy of this clade is paracytic stomata (no.
20). The Vaccinieae are clearly monophlyetic (d19, 100%
bootstrap) and are supported by the same morphological
characters as in the morphology-based analyses, with the
addition of the anther tubules (no. 41). Such tubules evidently
have evolved independently in a few other taxa,
e.g., Chamaedaphne and the Tepuia Diplycosia clade.
The remaining taxa, mainly members of the Gaultheria
group, form a very weakly supported clade (d1, 50%
bootstrap), which possibly is supported by the synapomorphy
of a base chromosome number of 11 (although
Andromeda has x 12). In addition, forked appendages
(no. 40) occur on the anthers of Zenobia, Gaultheria, and
Pernettya and may have been lost from the remaining
taxa. Within this group, Andromeda and Zenobia are sister
to a potential clade (d1, 63% bootstrap) containing
Chamaedaphne, Leucothoë, Tepuia, Diplycosia, Gaultheria,
and Pernettya. However, a core element, containing
Diplycosia, Tepuia, Gaultheria, and Pernettya is well
supported (d11, 100% bootstrap). Members of this clade
are united by the presence of methyl salicylate (lost in
some species of Gaultheria and Diplycosia). They may
also share the apomorphy of sepals that are fleshy and
colorful, but the latter feature is absent in Tepuia (and in
some species of Pernettya) and may have evolved inde-