Showing papers by "Elizabeth A. Zimmer published in 2003"

Family-level relationships of Onagraceae based on chloroplast rbcL and ndhF data

Abstract: Despite intensive morphological and molecular studies of Onagraceae, relationships within the family are not fully understood One drawback of previous analyses is limited sampling within the large tribe Onagreae In addition, the monophyly of two species-rich genera in Onagreae, Camissonia and Oenothera, has never been adequately tested To understand relationships within Onagraceae, test the monophyly of these two genera, and ascertain the affinities of the newly discovered genus Megacorax, we conducted parsimony and maximum likelihood analyses with rbcL and ndhF sequence data for 24 taxa representing all 17 Onagraceae genera and two outgroup Lythraceae Results strongly support a monophyletic Onagraceae, with Ludwigia as the basal lineage and a sister-taxon relationship between Megacorax and Lopezia Gongylocarpus is supported as sister to Epilobieae plus the rest of Onagreae, although relationships within the latter clade have limited resolution Thus, we advocate placement of Gongylocarpus in a monogeneric tribe, Gongylocarpeae Most relationships within Onagreae are weakly resolved, suggesting a rapid diversification of this group in western North America Neither Camissonia nor Oenothera appears to be monophyletic; however, increased taxon sampling is needed to clarify those relationships Morphological characters generally agree with the molecular data, providing further support for relationships

Phylogenetic analyses and perianth evolution in basal angiosperms

Abstract: Using a compartmentalization approach, we conducted phylogenetic analyses of the basalmost extant angiosperms using sequences from six genes (over 12,000 bp per taxon) from all three genomes (chloroplast-atpB, rbcL; nuclear- 18S rDNA, 26S rDNA; mitochondrial-matR, atpA). Trees resulting from parsimony and maximum likelihood analyses of the compartmentalized data are identical. We find strong support (100% for each node) for the earliest-branching angiosperms: Amborellaceae, Nymphaeaceae, and an Austrobaileyales clade (Illiciaceae, Schisandraceae, Trimeniaceae, Austrobaileyaceae). Whereas most recent studies using multiple genes provided poor resolution and support for relationships among the remaining basal angiosperms (Ceratophyllaceae, Chloranthaceae, Canellales ( = Winterales), Piperales, monocots, Magnoliales, Laurales), with compartmentalization, we find high levels (> 90%) of bootstrap support for relationships among these clades. Canellales and Piperales form a strongly supported (100%) sister group that is, in turn, sister to a well-supported (100%) clade of Laurales and Magnoliales. Canellales + Piperales and Magnoliales + Laurales form a well-supported magnoliid clade. Ceratophyllaceae are strongly supported (100%) as sister to the monocots; the monocot/Ceratophyllaceae clade is well supported (86%) as sister to all remaining angiosperms (Chloranthaceae, the magnoliid clade, and eudicots). The addition of entire 26S rDNA sequences clearly contributed to this increased internal support. We examined the diversification of perianth phyllotaxis, merosity, and differentiation using our phylogenetic hypothesis for angiosperms. Ancestral perianth phyllotaxis and merosity are equivocal for each node of the Amborellaceae, Nymphaeaceae, Austrobaileyales grade; however, an undifferentiated perianth is reconstructed as the ancestral state for the angiosperms. Trimery and whorled perianth phyllotaxis have played a major role in basal angiosperm perianth evolution and represent the ancestral states for the large Glade comprising all angiosperms other than Amborella, Nymphaeaceae, and Austrobaileyales. A differentiated perianth has apparently evolved multiple times.

Reconstructing ancestral patterns of colonization and dispersal in the Hawaiian understory tree genus Psychotria (Rubiaceae): a comparison of parsimony and likelihood approaches.

Abstract: Systematic and biogeographical relationships within the Hawaiian clade of the pantropical understory shrub genus Psychotria (Rubiaceae) were investigated using phylogenetic analysis of 18S-26S ribosomal DNA internal (ITS) and external (ETS) transcribed spacers Phylogenetic analyses strongly suggest that the Hawaiian Psychotria are monophyletic and the result of a single introduction to the Hawaiian Islands The results of phylogenetic analyses of ITS and ETS partitions alone give slightly different topologies among basal lineages of the Hawaiian clade; however, such differences are not well supported Relationships in the section Straussia clade in particular are not well resolved because of few nucleotide changes on internal branches, suggesting extremely rapid radiation in the lineage Parsimony and likelihood reconstructions of an- cestral geographical distributions using the topologies inferred from both parsimony and likelihood analysis of combined data and using different combinations of models and branch lengths gave highly congruent results However, for one inter- nal node (corresponding to the majority of the "greenwelliae" clade), parsimony reconstructions were unable to distinguish between three possible island states, whereas likelihood reconstructions resulted in clear ordering of possible states, with the island of Oahu slightly more probable than other islands under all but one model and branch length combination considered (the Jukes-Cantor-like model with branch lengths inferred under parsimony, under which conditions Maui Nui is more probable) A pattern of colonization from oldest to youngest islands was inferred from the phylogeny, using maximum parsimony and maximum likelihood Additionally, a much higher incidence of intraisland versus interisland spe- ciation was inferred (Ancestral character state reconstruction; biogeography; ETS; Hawaii; island evolution; ITS; molecular systematics; Psychotria)

A Preliminary Phylogeny of Alloplectus (Gesneriaceae): Implications for the Evolution of Flower Resupination

Abstract: Monophyly of the neotropical plant genus Alloplectus (Gesneriaceae) was tested using maximum parsimony and maximum likelihood phylogenetic analyses of molecular sequence data from the nuclear ribosomal (nrDNA) internal transcribed spacer region (ITS). As currently circumscribed, Alloplectus is polyphyletic and includes taxa in three different clades. The clade that contains the type species is described as Alloplectus sensu stricto and is characterized by the presence of resupinate flowers. The Alloplectus s.s. clade is weakly supported as the sister-group to Columnea. A separate clade of non- resupinate ''Alloplectus'' species nests within a paraphyletic Drymonia. A third taxon, Alloplectus cristatus, endemic to the Lesser Antilles and northwestern South America, is also resupinate and unresolved in a basal polytomy, removed from the other species of Alloplectus. The fourth taxon, Alloplectus peruvianus, which was originally described as Columnea peruviana ,i s strongly supported as nesting within Columnea. Resupination of flowers is an important feature that has not been previously reported and should be recognized as a morphological synapomorphy for Alloplectus s.s. Within the tribe Episcieae, flower resupination is a convergent feature that is independently derived in the Alloplectus s.s. clade, Alloplectus cristatus, and a clade comprising some Nematanthus species.

A phylogeny of the Munnoziinae (Asteraceae, Liabeae): circumscription of Munnozia and a new placement of M. perfoliata

Abstract: The tribe Liabeae (Compositae, Cicho- rioideae) comprises three subtribes, Liabinae, Munnoziinae, and Paranepheliinae. For one of these, the Munnoziinae, which contains the genera Munnozia, Chrysactinium, Erato, and Philoglossa, the nuclear ITS (internal transcribed spacer) region was sequenced to examine the monophyly of the subtribe and the core genus Munnozia within it. Thirty-six samples representing four currently recognized genera of Munnoziinae and two outgroups were included in this study. Mo- lecular phylogenetic analyses confirm the close relationship of Munnozia with Chrysactinium, and Erato with Philoglossa. However, the monophyly of the Munnoziinae and Munnozia is not support- ed, in disagreement with the current morpholog- ical findings. The discrepancies were attributed to the placements of Munnozia perfoliata outside the Munnoziinae and Munnozia ,a ndChrysactinium within Munnozia. The resulting tree indicates that first, M. perfoliata needs to be moved out of the munnoziinae and second, Chrysactinium originated from within Munnozia. For the first finding, morphological and palynological reevalu- ation of this species with allegedly related species reveals additional support in agreement with molecular data. Therefore we propose that the genus Munnozia be re-delimited to the members having black or dark brown anther theca and sordid or reddish pappus and re-organized.