The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Gilberto Ocampo - One of the best experts on this subject based on the ideXlab platform.
-
diversification of inflorescence types in portulaca Portulacaceae and its systematic implications
Phytotaxa, 2018Co-Authors: Gilberto Ocampo, Laura MairsanchezAbstract:Portulaca is the only genus in Portulacaceae and includes ca. 100 species with worldwide distribution. Inflorescence types in Portulaca have been used as an important character in infrageneric classifications and it has been suggested that capitula and solitary flowers derive from a cyme. The present paper focuses on the study of the diversification patterns of the inflorescence within Portulacaceae based on a phylogenetic approach. A phylogenetic framework was used to estimate the ancestral inflorescence type under parsimony and maximum likelihood criteria. The results, although ambiguous, suggest that a cymose inflorescence may have been the ancestral type for Cactineae. Diversification patterns within Portulacaceae are not clear, but it is plausible that capitula and solitary flowers are derived from a cymose inflorescence. In addition, the first two types may have evolved independently at least twice in the group. These results show that the inflorescence type has limited systematic utility, contrary to the current accepted infrageneric classifications of Portulaca , and only characterizes a group of Australian species with cymose inflorescences.
-
a new perennial species of portulaca Portulacaceae from central mexico
Phytotaxa, 2018Co-Authors: Gilberto OcampoAbstract:Portulaca juliomartinezii is described here as a new species from the Mexican states of Guanajuato and Queretaro. It is a perennial species with fusiform roots, magenta flowers, and a hemispheric operculum, a set of characters that segregate it from other taxa like P. mexicana and P. pilosa . Although the molecular phylogenetic analysis is not clear about the sister relationships of P. juliomartinezii , the new species was found to be member of a high-supported clade within the Pilosa clade.
-
rediscovery of a halophytic endemic and rare species of portulaca Portulacaceae from central argentina morphology and its phylogenetic position
Phytotaxa, 2017Co-Authors: Juan J Cantero, Gloria E Barboza, Gilberto OcampoAbstract:Portulaca ragonesei (Portulacaceae), an extreme holophyte species from Salina de Ambargasta, central Argentina, is here illustrated and re - described based on morphological evidence. In addition, molecular data shows that this endemic species is one of the earliest-divergent lineages of the Oleracea clade. This is a critically endangered species that can be morphologically distinguished by its sprouting geophytes habit, the linear leaves, and the presence of constriction at the apex of the pixidium where only one seed is found.
-
systematic implications of seed morphological diversity in Portulacaceae caryophyllales
Plant Systematics and Evolution, 2015Co-Authors: Gilberto OcampoAbstract:The Portulacaceae are a monogeneric family with around 100 species distributed around the world. Seed morphology in the group is diverse, but its systematic significance is controversial, and its diversification patterns are unknown. In this study, the seed morphology and size of 63 samples representing 49 species, nine varieties, and two cultivars are evaluated under a phylogenetic framework. Eight seed features (including size) and DNA sequences were analyzed with parsimony and Bayesian methods and seed diversification patterns were estimated using ancestral character reconstruction under a parsimony approach. Analyses of the seed features retrieved an unresolved phylogeny, contrary to the phylogenetic estimate of the DNA data that was consistent with the clades and subclades obtained in previous studies. The analyses of a combined data matrix of seed features and DNA sequence data did not improve nodal support for the relationships within Portulacaceae. Although the hypothesis testing procedures could not reject the monophyly of major clades within Portulacaceae, ancestral character reconstruction analyses showed that the seed features are homoplasious and do not represent synapomorphies for those clades. Some character states were predominantly present in one clade and were rarely found in others. Seed size seemed to be relatively constant throughout the evolutionary history of Portulacaceae (<0.85 mm long), with multiple independent events of size increase. Although seed features do not reflect the evolutionary history of Portulacaceae, they still have a high taxonomic value, especially when used along with other features.
-
Systematic implications of seed morphological diversity in Portulacaceae (Caryophyllales)
Plant Systematics and Evolution, 2014Co-Authors: Gilberto OcampoAbstract:The Portulacaceae are a monogeneric family with around 100 species distributed around the world. Seed morphology in the group is diverse, but its systematic significance is controversial, and its diversification patterns are unknown. In this study, the seed morphology and size of 63 samples representing 49 species, nine varieties, and two cultivars are evaluated under a phylogenetic framework. Eight seed features (including size) and DNA sequences were analyzed with parsimony and Bayesian methods and seed diversification patterns were estimated using ancestral character reconstruction under a parsimony approach. Analyses of the seed features retrieved an unresolved phylogeny, contrary to the phylogenetic estimate of the DNA data that was consistent with the clades and subclades obtained in previous studies. The analyses of a combined data matrix of seed features and DNA sequence data did not improve nodal support for the relationships within Portulacaceae. Although the hypothesis testing procedures could not reject the monophyly of major clades within Portulacaceae, ancestral character reconstruction analyses showed that the seed features are homoplasious and do not represent synapomorphies for those clades. Some character states were predominantly present in one clade and were rarely found in others. Seed size seemed to be relatively constant throughout the evolutionary history of Portulacaceae (
Mark A Hershkovitz - One of the best experts on this subject based on the ideXlab platform.
-
ribosomal and chloroplast dna evidence for diversification of western american Portulacaceae in the andean region
Gayana Botanica, 2006Co-Authors: Mark A HershkovitzAbstract:Sequences of the ribosomal DNA internal transcribed spacer (ITS) region and the chloroplast DNA ycf3-trnS intergenic spacer were determined for 183 samples representing Chilean and non-Chilean taxa of western American Portulacaceae and their outgroups. The data refine previous inferences of generic circumscriptions and interrelations. In particular, the data reveal that an earlier circumscription of Cistanthe Spach is polyphyletic and also reveal a North American clade comprising Claytonia L., Lewisia Pursh, Lewisiopsis R. Govaerts, and Montia L. Within the South American genera, two patterns emerge from the data: (1) in some cases, interspecific divergence is remarkably low given the markers employed and estimated number of species; and (2) where divergence of one or both markers offer phylogenetic resolution, there is conflict between them and/or with morphology. The patterns can be evaluated in terms of two phenomena: (1) morphological/ecological radiation proceeding much faster than sequence divergence; and (2) frequent hybridization. In the latter case, the gene tree patterns may distort the true timing and cladistic pattern of morphological and ecological diversification. At present, the degree to which evidence for hybridization among the Chilean Portulacaceae will prove to be the rule or the exception is unclear. Nonetheless, spatial and temporal ecological patterns in Chile generally favor hybrid formation and persistence.
-
ribosomal dna evidence and disjunctions of western american Portulacaceae
Molecular Phylogenetics and Evolution, 2000Co-Authors: Mark A Hershkovitz, Elizabeth A ZimmerAbstract:Abstract Phylogenetic analysis of ribosomal DNA internal transcribed spacer sequences from 35 members of western American Portulacaceae plus seven Portulacaceae outgroups generally supports morphologically based interpretations of multiple intercontinental disjunctions. The data neither support nor refute monophyly of the western American group but strongly support a group comprising the western American taxa plus Phemeranthus, the only strictly American genus of the morphology-based eastern American/African group of Portulacaceae, along with the Australian genus Parakeelya. Support is strong for the monophyly of Calandrinia, Montiopsis, Lewisia, Claytonia, and Montia, along with a sister relationship of the last two. The data neither strongly support nor refute the morphologically based diagnosis of Cistanthe, but they strongly support a clade including the North American Cistanthe section Calyptridium and the South American Cistanthe sections Amarantoideae and Philippiamra. The internal transcribed spacer data fail to resolve the phylogenetic relationships among most of the western American lineages, suggesting either rapid radiation or, alternatively, erratic evolution of the internal transcribed spacer. The internal transcribed spacer and morphological evidence together suggest that in this group there have been 8–13 dispersal and colonization events across >2000 km (1 for every 15–26 extant species in this group). The internal transcribed spacer data document complex molecular evolutionary patterns, including strong substitution biases, among-site rate heterogeneity, positional bias for deamination-type substitutions, nonstationarity, and variable rates of insertion/deletion. Our phylogenetic conclusions, however, do not appear to be sensitive to these patterns.
-
revised circumscriptions and subgeneric taxonomies of calandrinia and montiopsis Portulacaceae with notes on phylogeny of the portulacaceous alliance
Annals of the Missouri Botanical Garden, 1993Co-Authors: Mark A HershkovitzAbstract:Cladistic analysis of Portulacaceae supports a revised taxonomy of Calandrinia sensu lato. Calandrinia, as here circumscribed, comprises ca. 14 western American species in three sections: Calandrinia, Acaules, and Monocosmia. Previous taxonomies classified over 100 species in Calandrinia but recognized Monocosmia as a distinct genus. Calandrinia sects. Calandrinia and Monocosmia are probably cladistically nested in section Acaules and are not sister groups of either Rumicastrum or Montia, as proposed in a previous cladistic analysis. Montiopsis Kuntze, traditionally included in Calandrinia, comprises ca. 15 western South American species in two subgenera, Montiopsis and Dianthoideae (...)
-
leaf morphology of calandrinia and montiopsis Portulacaceae
Annals of the Missouri Botanical Garden, 1993Co-Authors: Mark A HershkovitzAbstract:Calandrinia sect. Calandrinia, C. sect. Monocosmia, and some species of C. sect. Acaules share identical leaf blade and petiolar morphology, fimbrial veins, predominantly brachytetracytic and staurocytic stomata surrounded by a cycle of subsidiary-like cells, and unicellular ribbed trichomes or papillar trichomes. Other species of C. sect. Acaules have irregularly brochidodromous venation without a fimbrial vein, predominantly brachyparacytic stomata, and/or no trichomes; venation and stomatal morphology in these species is similar to that found in Montiopsis. Leaves of Montiopsis lack petioles, have glandular or eglandular, uniseriate- and/or multiseriate-multicellular trichomes (although some examined specimens of M. subg. Dianthoideae appear to be glabrous), and generally have brachyparacytic stomata (although some examined specimens of subgenus Dianthoideae have a small proportion of brachytetracytic/staurocytic stomata with an outer cycle of cells) (...)
-
leaf morphology and taxonomic analysis of cistanthe tweedyi nee lewisia tweedyi Portulacaceae
Systematic Botany, 1992Co-Authors: Mark A HershkovitzAbstract:Cistanthe tweedyi (Portulacaceae) is a rare perennial herb endemic to the Cascade Mountains of northern Washington and adjacent British Columbia. It has heretofore been classified in Lewisia, probably because of the persistent, yet erroneous, characterization of its fruit dehiscence as circumscissile, as in Lewisia, rather than valvate, as in most other Portulacaceae. Cladistic affinity of C. tweedyi to Cistanthe is evidenced by its unequal inflorescence bracts (a synapomorphy of the genus) and by the presence of several characters that show homoplasy in Portulacaceae but do not occur in combination outside of Cistanthe, including wide-petiolate leaves, festooned brochidodromous venation, an apically diminished primary vein, predominantly brachyparacytic and similar stomata, and strophiolate seeds with colliculate sculpture and micropylar hooks. Cistanthe tweedyi lacks sinuous and ribbon-like veins, which are otherwise rarely absent in Cistanthe. Cistanthe tweedyi lacks other characteristics plausibly synapomorphic for all or part of Lewisia, including glandulardentate sepals and bracts, cladodromous leaf venation, and laterocytic stomata. The chromosome base number of Cistanthe tweedyi, n = 46, is possibly based on n = 11-a number common in Cistanthe, but rare in Lewisia. Cistanthe tweedyi constitutes a monotypic sect. Strophiolum within Cistanthe. Its precise phylogenetic position and biogeographic origin remain uncertain. Cistanthe tweedyi (A. Gray) Hershkovitz (figs. 1-3), formerly Lewisia tweedyi (A. Gray) Robinson in A. Gray, is a rare, perennial herb endemic to the Cascade Mountains of northern Washington and adjacent British Columbia. Gray (1887) described the species as Calandrinia tweedyi and placed it in sect. Pachyrhizae, which he erected to accommodate several species of Portulacaceae with circumscissile fruit dehiscence. Robinson (in Gray 1897) transferred Calandrinia Kunth sect. Pachyrhizae into Lewisia Pursh, where Cistanthe tweedyi has remained except during a brief hiatus in Oreobroma Howell (Howell 1893, Rydberg 1932). Hohn (1975), however, reported that the capsule of Cistanthe tweedyi has valvate dehiscence (fig. 2), rather than the distinctive form of circumscissile dehiscence characteristic of Lewisia. She also emphasized that the strophiolate seeds characteristic of this species (fig. 4) are otherwise absent in Lewisia. Hohn proposed that Cistanthe tweedyi be assigned to a monotypic sect. Strophiolum in Lewisia, and she further suggested that this species might merit a separate generic status. Mathew (1989) argued that Cistanthe tweedyi was best retained in Lewisia, but he formally classified it in the monotypic L. subg. Strophiolum B. Mathew. It should be emphasized, however, that if Gray had correctly described the fruit dehiscence of Cistanthe tweedyi, it would likely have remained in Calandrinia and never have been assigned to Lewisia. The present paper synthesizes existing data and new evidence on leaf morphology to help demonstrate that Cistanthe tweedyi belongs in Cistanthe Spach and not in Lewisia. Understanding the logic of the proposed transfer requires background on revised taxonomic interpretations of Calandrinia. Calandrinia s.l. includes 100150 species of America and Australia (Hershkovitz, in press a; Kelley 1973; McNeill 1974). In a cladistic analysis of Portulacaceae, Carolin (1987) found Calandrinia to be paraor polyphyletic. For example, he found that several largely South American sections of Calandrinia (cf. table 1), together with the South American Philippiamra Kuntze and the North American Calyptridium Nutt. in Torrey and A. Gray (incl. Spraguea Torrey), formed a monophyletic group defined by the presence of unequal inflorescence bracts. Carolin (1987, in press) proposed combining these sections of Calandrinia and Philippiamra into Cistanthe, but he retained Calyptridium as a distinct genus. I reanalyzed (Hershkovitz 1991a, 1991b, in press a) Carolin's (1987) data in the light of additional evidence from leaf morphology and largely corroborated the case for recognizing Cistanthe, but I found
I Paraguatey - One of the best experts on this subject based on the ideXlab platform.
-
occurrence of inducible crassulacean acid metabolism in leaves of talimum triangulare Portulacaceae
Journal of Experimental Botany, 1991Co-Authors: Ana Herrera, J Delgado, I ParaguateyAbstract:In this paper we report for the first time the occurrence of an inducible weak CAM in leaves of Talinum triangulare (Jacq.) Willd. This plant is a terrestrial perennial deciduous herb with woody stems and succulent leaves which grows under full exposure and in the shade in northern Venezuela. Plants grown in a greenhouse ('sun' plants) and a growth cabinet ('shade' plants) with daily irrigation showed CO2 uptake only during the daytime (maximum rate, 40ftmol m~2 s"') and a small acid accumulation during the night (60 f±mol H+ g"1 FW). Twenty-four hours after cessation of irrigation, no CO 2 exchange was observed during part of the night. Dark fixation reached a maximum (1 0 ^mol CO2 m ~2 s"', 100 /imol H + g"' FW) on day 9 of drought. By day 30 almost no gas exchange was observed, while acid accumulation was still lO^mol H+ g"1 FW. Rewatering reverted the pattern of CO2 exchange to that of a C3 plant within 24 h. Daytime and night-time phosphoenolpyruvate carboxylase activity increased up to 100% (shade) and 62% (sun) of control values after 10 and 15 d of drought, respectively. Light compensation point and saturating irradiance were similar in well-watered sun and shade plants, values being characteristic of sun plants. CAM seems to be important for the tolerance of plants of this species to moderately prolonged (up to 2 months) periods of drought in conditions of full exposure as well as shade, and also for regaining high photosynthetic rates shortly after irrigation.
Elizabeth A Zimmer - One of the best experts on this subject based on the ideXlab platform.
-
molecular evidence resolving the systematic position of hectorella Portulacaceae
Systematic Botany, 2006Co-Authors: Wendy L Applequist, Warren L Wagner, Elizabeth A Zimmer, Molly NepokroeffAbstract:The taxonomic position of Hectorella caespitosa and Lyallia kergelensis, caespitose plants endemic to New Zealand and to the Kerguelen Archipelago of Antarctica, respectively, remains controversial. Some authors place them within Portulacaceae, but a slight majority of recent authorities treat them as a separate family, Hectorellaceae. Sequences of the chloroplast genes rbcL, ndhF, and matK were obtained from H. caespitosa and added to previously published sequences from Portulacaceae and related families. These data strongly supported the derived position of Hectorella within a clade consisting of western American members of Portulacaceae; the sister group of Hectorella was a clade including Montia, Claytonia, and Lewisia. Implications for taxonomy are discussed. In order to accomodate monophyly in tribal-level classification while preserving current tribes Montieae and Lewiseae, the new tribe Hectorelleae is proposed for the family Portulacaceae.
-
ribosomal dna evidence and disjunctions of western american Portulacaceae
Molecular Phylogenetics and Evolution, 2000Co-Authors: Mark A Hershkovitz, Elizabeth A ZimmerAbstract:Abstract Phylogenetic analysis of ribosomal DNA internal transcribed spacer sequences from 35 members of western American Portulacaceae plus seven Portulacaceae outgroups generally supports morphologically based interpretations of multiple intercontinental disjunctions. The data neither support nor refute monophyly of the western American group but strongly support a group comprising the western American taxa plus Phemeranthus, the only strictly American genus of the morphology-based eastern American/African group of Portulacaceae, along with the Australian genus Parakeelya. Support is strong for the monophyly of Calandrinia, Montiopsis, Lewisia, Claytonia, and Montia, along with a sister relationship of the last two. The data neither strongly support nor refute the morphologically based diagnosis of Cistanthe, but they strongly support a clade including the North American Cistanthe section Calyptridium and the South American Cistanthe sections Amarantoideae and Philippiamra. The internal transcribed spacer data fail to resolve the phylogenetic relationships among most of the western American lineages, suggesting either rapid radiation or, alternatively, erratic evolution of the internal transcribed spacer. The internal transcribed spacer and morphological evidence together suggest that in this group there have been 8–13 dispersal and colonization events across >2000 km (1 for every 15–26 extant species in this group). The internal transcribed spacer data document complex molecular evolutionary patterns, including strong substitution biases, among-site rate heterogeneity, positional bias for deamination-type substitutions, nonstationarity, and variable rates of insertion/deletion. Our phylogenetic conclusions, however, do not appear to be sensitive to these patterns.
Mario Geraldo De Carvalho - One of the best experts on this subject based on the ideXlab platform.
-
chemical compounds isolated from talinum triangulare Portulacaceae
Food Chemistry, 2014Co-Authors: Ana Paula De O Amorim, Almir Ribeiro De Carvalho, Norberto Peporine Lopes, Rosane Nora Castro, Marcia C C De Oliveira, Mario Geraldo De CarvalhoAbstract:Abstract This first phytochemical study of Talinum triangulare Leach (Portulacaceae), also known as ‘cariru’, which is a commonly consumed food in Northern Brazil, allowed the isolation and structural determination of four new compounds: one acrylamide, 3-N-(acryloyl, N-pentadecanoyl) propanoic acid ( 5 ), and three new phaeophytins named (15 1 S , 17 R , 18 R )-Ficuschlorin D acid (3 1 ,3 2 -didehydro-7-oxo-17 3 -O-phytyl-rhodochlorin-15-acetic acid), ( 13 ), Talichorin A (17 R , 18 R )-phaeophytin b-15 1 -hidroxy, 15 2 ,15 3 -acetyl-13 1 -carboxilic acid ( 14 ), and (15 1 S , 17 R , 18 R )-phaeophytin b peroxylactone or (15 1 S , 17 R , 18 R )-hydroperoxy-ficuschlorin D ( 16 ), together with twelve known compounds, including four phaeophytins ( 11 , 12 , 15 and 17 ). The structures of the compounds were established on the basis of 1D and 2D NMR, IR, HRESI-MS spectra, including GC–MS, and HPLC–UV analysis, as well as comparisons with the literature data. The CD spectra data analysis were used to define the absolute configuration of phaeophytins 12 (13 2 R , 17 R , 18 R )-13 2 -hydroxyphaeophytin a, 13 and 16 , 15 (15 1 S , 17 R , 18 R )-3 1 ,3 2 -didehydro-15 1 -hydroxyrhodochlorin-15-acetic acid δ-lactone-15 2 -methyl- 17 3 -phytyl ester and 17 (17 R , 18 R )-purpurin 18-phytyl ester.