WERNER, N. MISA* AND ROBERT A. PRICE. Department of Botany, University of Georgia, Athens, GA 30602. - Phylogeny and morphological evolution of Marcgraviaceae: insights from three chloroplast genes.
Marcgraviaceae comprises seven genera and approximately 130 species
distributed from southern Mexico to northern Bolivia including the
Caribbean islands. Distinctive morphological features include
hemiepiphytic habit, hypophyllous glands, reversible heteroblasty, and
highly modified bracts which are transformed into pitcher-like
extrafloral nectaries. Phylogenetic analysis of rbcL sequence
data strongly supports the monophyly of the family and an alliance
with Tetrameristaceae, Pellicieraceae, and Balsaminaceae. A possible
sister-group relationship of Marcgraviaceae with Tetrameristaceae +
Pellicieraceae is weakly supported by this analysis. Marcgraviaceae
exhibit an unusually low amount of sequence divergence in comparison
to their close relatives. Relationships within the family are
investigated using trnL-F and ndhF sequence comparisons.
These data resolve two major lineages within Marcgraviaceae
corresponding to subfamilies Marcgravioideae and Noranteoideae. The
monogeneric Marcgravioideae are united by several morphological
synapomorphies and a 4 bp indel in the trnL intron. In
contrast, subfamily Noranteoideae appears to be delimited by
plesiomorphic morphological characters, but it is supported by
molecular data. Despite considerable morphological heterogeneity
within Noranteoideae, our sequence data do not resolve currently
recognized genera as monophyletic groups.
Key words: Marcgraviaceae, molecular systematics, morphological evolution, phylogeny