A central tenet of evolutionary biology is that environmental change is the prime driving force behind speciation and the genesis of evolutionary novelty. While gradual, long-term environmental change may be an important stimulus for speciation, it is not clear that such change would generate highly divergent phenotypic, physiological, and life history attributes, and disparate ecological tolerances, as described in numerous angiosperm genera. I propose that niche shifts rather than long-term environmental change are the primary drivers of evolutionary novelty within genera. This argument is based on the differences in the dynamics of speciation through gradual change and in the dynamics of speciation through niche transitions. Ecological speciation is a prospective process that involves the invasions of new niches in space. Geographical or vicariant speciation is a responsive process involving changes dictated selectively or randomly by environmental gradients in time. Niche conservatism may limit major adaptive shifts in time.

Nucleotide sequences for six nuclear loci and one chloroplast region were used to reconstruct phylogenetic relationships in Sphagnum section Acutifolia. The combined data matrix, which includes 136 accessions (129 ingroup taxa and seven outgroups) and 5126 nucleotide sites, was analyzed using Bayesian inference. Most of the individual morphospecies commonly recognized in the section were represented by multiple populations, in some cases by up to 16 accessions from throughout the Northern Hemisphere. Results of the combined seven-locus analysis resolved many of the species as monophyletic, but the deeper nodes were generally without support. Separate analyses of single-locus data sets revealed significant conflicts, indicating gene flow among both closely and more distantly related species within the section. The sequence data allowed likely parentage to be identified for several species of hybrid origin, and identified individual accessions that appear to be genetic admixtures. Taxonomic conclusions that can be made from the analyses include: 1. Sphagnum wulfianum and S. aongstroemii should both be included in section Acutifolia, 2. S. subtile cannot be separated from S. capillifolium, and the two should be synonymized, 3. S. capillifolium and S. rubellum each contain a monophyletic core of populations and should be retained as separate species, but 4. S. rubellum cannot be separated from S. andersonianum and S. bartlettianum and the three should be merged, 5. S. tenerum is highly differentiated from S. capillifolium and should be treated as a separate species, 6. interspecific mixed ancestry is demonstrated for S. russowii (a likely allopolyploid), S. skyense, S. arcticum, and S. olafii. Interspecific recombination appears to be rather common in section Acutifolia, yet species, for the most part, maintain cohesiveness.

The phylogenetic integrity and relationships of the pleurocarpous moss Hypnodendron and several potentially related taxa are investigated using chloroplast rbcL, trnL-F, and rps4 sequence data, the mitochondrial nad5 region, and a set of 29 morphological characters. Strong support is obtained for the recognition of a monophyletic group, the “hypnodendroid pleurocarps,” that includes Hypnodendron, Braithwaitea, Pterobryella praenitens, the Cyrtopodaceae, Spiridentaceae, and Racopilaceae. This clade is resolved as sister to the Hypnanae with moderately strong support. Hypnodendron is paraphyletic, with H. section Sciadocladus resolved as sister to Pterobryella praenitens and outside of a very well supported clade that includes the other taxa of Hypnodendron in addition to the Spiridentaceae and Cyrtopodaceae. Chloroplast and mitochondrial sequence data show a high degree of congruence, and confidence in critical nodes is increased by long branches, high support values, and indels corresponding to radical modification of sequence and secondary structure within the nad5 group I intron. Based on morphological character state optimisation the hypnodendroid pleurocarps comprise a clade that includes plesiomorphically dendroid, palmate/umbellate terrestrial plants in addition to a number of derived lineages representing adaptive shifts towards epiphytism. These include the prostrate/creeping Racopilaceae, the dendroid-pinnate species in Hypnodendron section Phoenicobryum, and the simple, large-leaved Spiridentaceae and Cyrtopodaceae. Our data also support recognition of the hypnodendroid pleurocarps at the ordinal or superordinal level.

The systematics of the Asplenium seelosii complex have been debated for a long time. This complex includes strictly rupicolous plants that live on limestone cliffs mainly in mountains of southwest Europe: the Alps, the Pyrenees, and several mountain ranges of the Eastern Iberian Peninsula. The disjunct distribution of the populations and several morphological characters, i.e., leaf indumentum and the structure of the perispore, have been used to distinguish species and subspecies. The goal of this study was to evaluate the different systematic treatments of this complex by means of isozyme electrophoresis. Seventeen populations throughout the range of the complex were studied, and 15 enzymatic systems were assayed. There was no within population genetic variation and genetic identity between populations varied widely. Analysis of isozymic data clearly differentiated two groups corresponding to the species proposed, Asplenium seelosii and A. celtibericum, but these data do not support the recognition of subspecies in this complex.

Multivariate analyses of qualitative and quantitative characters taken from herbarium specimens of Calyptrogyne H. Wendl. (Palmae), together with analysis of geographic distributions, reveals 27 groups of specimens. Application of the Phylogenetic Species/Subspecies Concept to these groups gives 18 species and 13 subspecies, giving a total of 27 taxa in the genus. Eight species (C. tutensis, C. fortunensis, C. sanblasensis, C. baudensis, C. deneversii, C. coloradensis, C. panamensis, C. osensis) and seven subspecies (C. costatifrons subsp. occidentalis, C. costatifrons subsp. dariensis, C. allenii subsp. centralis, C. panamensis subsp. centralis, C. panamensis subsp. tutensis, C. panamensis subsp. occidentalis, C. ghiesbreghtiana subsp. hondurensis) are new, and two new combinations are made (C. ghiesbreghtiana subsp. spicigera, C. ghiesbreghtiana subsp. glauca). These taxa are distributed from southern Mexico to northwestern Colombia, with the greatest diversity in western Panama.

Poa, with about 575 species, is the largest genus of grasses, and has diversified throughout temperate, boreal, and arctic regions, and similar habitats through the tropics. This new phylogenetic study of Poa based on analysis of restriction site data from PCR amplified regions of chloroplast DNA (trnT-trnF, trnF-trnV, trnV-rbcL, rbcL-ORF106, trnH-trnK) expands previous sampling in the genus to where 1/5 to 1/6 of the species have been characterized for chloroplast DNA types. A broad phylogenetic structure detected in a previous study using restriction site mapping of Poa chloroplast DNA gained additional and robust support. Accounting for extended intra- and extrageneric sampling, Poa remains monophyletic if Austrofestuca and Parodiochloa are included as sections within P. subg. Poa, and if Poa subg. Andinae is removed from the genus. Two new combinations are made: Poa sect. Austrofestuca and Poa sect. Parodiochloa. This new analysis supports the recognition of five major clades within Poa: 1) ArcSyl, Poa subg. Arctopoa sects. Arctopoa and Aphydris, and P. subg. Poa sect. Sylvestres; 2) BAPO, P. subg. Poa sects. (Bolbophorum Alpinae) (Parodiochloa Ochlopoa); 3) SPOSTA, P. subg. Poa sects. (Secundae (Pandemos (Orienos Stenopoa Tichopoa Abbreviatae))); 4) PoM, P. subg. Poa sects. (Poa Macropoa); 5) HAMBADD, P. subg. Poa sects. (Homalopoa, Acutifolae, Brizoides, Madropoa, Austrofestuca, Dasypoa, Dioicopoa, and informal groups “Punapoa” and “Australopoa”). These clades diverge in the following arrangement from the outgroups: ArcSyl (BAPO (SPOSTA ((PoM) (HAMBADD))).

Very little is known about the small, tropical, monogeneric monocotyledon family Lowiaceae within the order Zingiberales. The phylogenetic position of Lowiaceae within Zingiberales is unclear, as are relationships within its single genus Orchidantha, which includes at least 16 species. This paper presents a phylogenetic analysis of Zingiberales based on 613 parsimony informative characters of the plastid matK gene, the trnL-trnF region, the rps16 intron, and a conservative part of the nuclear ribosomal ITS region (part of the 18S, 5.8S, and 26S rDNA). The resulting single most parsimonious tree indicates that Lowiaceae is sister to all the remaining families of Zingiberales. An analysis of the family (14 species) based on a data set consisting of six plastid and nuclear DNA regions, includes the first use of a cam intron for estimating phylogeny. The results suggest that the nuclear calmodulin (cam) intron may be useful for other lower taxonomic level phylogenetic analyses. In the resulting tree all Bornean species of Orchidantha form a strongly supported monophyletic group. An equally strongly supported clade within the Bornean group contains the species distributed in Sabah (Malaysia) and Brunei. The species from mainland Asia form a poorly supported group because of the unclear position of Orchidantha chinensis. However, the four Malay Peninsula species with flowers possessing a white labellum form a strongly supported monophyletic group.

Fossils are widely used as calibration points in molecular-based dating studies, but their placement on a phylogenetic tree of extant species is always highly problematic. We explore some of the problems linked to calibration with fossils, in particular their position on the tree, and emphasize the use of multiple calibration points to obtain better estimates. We use a phylogenetic analysis of Betulaceae based on nuclear ribosomal DNA sequences (5S spacer and ITS) as a case study and estimated divergence times within the family using the nonparametric rate smoothing method of Sanderson and five calibration points from the extensive fossil record of this family. To assess the effects of assumptions relating to the positions of key fossils with respect to stem lineages versus crown groups, we calculated age estimates by placing each fossil subsequently on the stem lineage node and crown group node, and then determined the median value of the resulting ten estimates for each node. Using maximum likelihood and DELTRAN and ACCTRAN parsimony branch lengths, we found that the age of the crown group and stem lineage of Betulaceae vary from 115.2 to 130.6 million years and 211.2 to 302.6 million years (Aptian or before). These results are older than current paleobotanical data. We calculated paleobotanical confidence intervals using methods based on the occurrence of fossils on a stratigraphic column and the lengths of the gaps between these occurrences. We apply these methods to the fossil record of Alnus and related extinct genera; however, only in some cases were molecular- and fossil-based age estimates reconciled.

A new species, Stillingia yungasensis, from the “Yungas Tucumano-Bolivianas” forest (northwestern Argentina and southern Bolivia) is described and illustrated, including data on habitat, distribution, phenology, and a key to the new species and closest taxa. Stillingia yungasensis may be one of the most basal taxa within Series Oppositifoliae. No other species of Stillingia is sympatric with S. yungasensis, and its distribution supports a recent subdivision of the Yungas forests into two distinct phytogeographical units. Unlike the remaining species of Series Oppositifoliae, S. yungasensis is relatively frequent within its habitat.

The circumscription of the Old World Passiflora subgenus Decaloba supersection Disemma has been problematic for more than one hundred years. Supersection Disemma consists of 22 Old World species found throughout mainland Asia, Southeast Asia, Australia, and the Pacific. They show great morphological diversity, possessing cup-shaped to tubular flowers and both branched and unbranched inflorescences. These features have been used to link species in Disemma to New World members of subgenus Decaloba, resulting in the widespread suspicion that Disemma is not monophyletic. Plastid (trnL-F intron and spacer) and nuclear (ITS) DNA sequences were used to test the monophyly of supersection Disemma and reconstruct phylogenetic relationships within this group. Two monotypic genera, Hollrungia and Tetrapathaea, were included in this analysis based on their strong morphological similarity to Passiflora, and the Austral-Pacific distribution they share with many of the Old World species. Supersection Disemma is monophyletic, containing two distinct Asian and Australian lineages. Hollrungia and Tetrapathaea are strongly supported as members of Passiflora, though their exact relationships to each other are not resolved. The tubular floral morphology in the Australian species is not homologous with that in the New World species. However, the tubular morphology of P. hollrungii from Papua New Guinea is homologous to the New World tubular condition. The architecture of inflorescences in Disemma is more similar to that in closely related species of Passiflora than to other genera of Passifloraceae.

The new species Serjania chacoensis from Bolivia and Brazil, Serjania souzana from Bolivia, Brazil, and Peru, and Serjania paranensis from the state of Paraná, Brazil, all belonging to Serjania sect. Serjania, are described, illustrated and contrasted to their putatively closest relatives.

Resumen. Las tres nuevas especies Serjania chacoensis de Bolivia y Brasil, Serjania souzana de Bolivia, Brasil y Perú, y Serjania paranensis del estado de Paraná en Brasil, todas pertenecientes a Serjania sección Serjania son aquí descritas, ilustradas y contrastadas con los que se estiman ser sus parientes más cercanos.

The wood structure of 78 species from 27 genera representing the woody primuloids (Maesaceae, Myrsinaceae, and Theophrastaceae) was investigated using light microscopy (LM) and scanning electron microscopy (SEM). Results indicated that the ray structure, the nature of mineral inclusions, and the occurrence of breakdown areas in rays can be used to separate the three primuloid families from each other. Within Ericales, the presence of exclusively multiseriate rays is synapomorphic for Myrsinaceae and Theophrastaceae, and the occurrence of breakdown areas in rays is synapomorphic for Myrsinaceae. Within Myrsinaceae, the wood structure of the mangrove genus Aegiceras differs because it has short vessel elements that are storied, non-septate fibers, a combination of low uni- and multiseriate rays, and multiseriate rays with exclusively procumbent body ray cells. The aberrant wood anatomy of Coris and Lysimachia can be explained by their secondary woodiness. Within Theophrastaceae, Clavija and Theophrasta can be distinguished from Bonellia, Jacquinia, and Deherainia. The recent division of Jacquinia s.l. into Jacquinia s.s. and Bonellia is supported by a difference in mineral inclusions.

Analysis of the trnT-trnL spacer, the trnL intron, the trnL-trnF spacer, and the rps16 intron of 106 species in 34 of the 45 genera of New World Asclepiadeae in the former subtribes Metastelmatinae, Oxypetalinae, and Gonolobinae shows that these genera form a well-supported clade (“MOG”). The small Andean genus Pentacyphus is sister to the remaining MOG clade. The former Gonolobinae form a well-supported subclade closely related to members of Tassadia, Funastrum, and former Oxypetalinae. The only genera that are monophyletic as presently circumscribed are Tassadia and Funastrum. The separation of Tweedia from Oxypetalum is justified by our results. Philibertia is monophyletic only if Amblystigma, Fontellaea, Melinia, Mitostigma, and Podandra are also included. Most species of Blepharodon and Hemipogon are not monophyletic with the respective type species. Some former Astephanus and Cynanchum species as well as the monotypic Grisebachiella are imbedded in Diplolepis (D. descolei, D. geminiflora, D. hieronymi, D. boerhaviifolia, and D. nummulariifolia). The neglected tribe Orthosieae is recognized at subtribal level, Orthosiinae. Chromosome numbers (as far as known) indicate a tendency for reduction in several clades. This study provides a framework for future study of the American MOG genera and highlights areas that need further attention.

Zaluzianskya (Scrophulariaceae s.s., tribe Manuleeae) is a diverse genus of 55 species of annual and perennial herbs, endemic to southern Africa. This study used DNA sequence data from the nrDNA ITS regions, rpl16, and trnL-trnF to produce the first broad phylogenetic hypotheses for Zaluzianskya, allowing the first tests of the monophyly of the genus and its sections, as well as an examination of character evolution. Reyemia nemesioides was placed within Zaluzianskya with strong support. This is consistent with several morphological characteristics of both species of Reyemia. Sections Zaluzianskya and Holomeria are not monophyletic. The single species sampled from section Macrocalyx (Z. mirabilis) was nested within section Nycterinia according to the chloroplast and combined data, but placed sister to Nycterinia according to the ITS data. Several species do not form clades. Populations of Z. villosa and Z. gracilis were nested within a Z. affinis clade while Z. divaricata was nested within a Z. pusilla clade. Finally, populations of the sole day-flowering species within section Nycterinia, Z. microsiphon, were separated on the phylogenies. The source of this division is unknown but could be hybridization or convergent evolution via pollinator selection. Analyses suggest that the plesiomorphic condition for Zaluzianskya is annual, distributed within arid regions. Subsequent derivations of a perennial life history appear associated with distribution in relatively mesic regions.

Physalis (75 species, Solanaceae) is most diverse in Mexico, with only the type, P. alkekengi, native to the Old World. Interspecific relationships are poorly known, and despite the distinctive inflated fruiting calyces, generic limits remain uncertain. Sequence data from part of the nuclear gene waxy (622 bp) and the internal transcribed spacer of the nrDNA (652 bp) were used to generate a phylogeny of subtribe Physalinae. Thirty-five species of Physalis and eight physaloid genera were sequenced. Data analysis included Bayesian and maximum parsimony methods. The Physalinae was monophyletic, but while the morphologically typical Physalis species formed a strongly supported clade, the morphologically atypical species made the genus paraphyletic. A grade of physaloid genera (Quincula, Oryctes, and Chamaesaracha) and Physalis subgenus Physalodendron separate P. alkekengi, P. carpenteri, and P. microphysa from other Physalis species. The Physalis clade consists of Margaranthus and species with solitary yellow flowers and highly inflated calyces. Most sections of Physalis do not appear to be monophyletic. Leucophysalis viscosa and the Central American physaloid genera Brachistus, Tzeltalia, and Witheringia formed a clade at the base of the Physalinae.