1,720,964 research outputs found
A New Species of Brachystele (Spiranthinae, Orchidaceae) with Nonresupinate Flowers from Central East Argentina
No full textA new spiranthoid orchid species recently discovered in the central-eastern region of Argentina, is described, and illustrated.The phylogenetic position of the new taxa was inferred from three molecular makers: the nuclear ribosomal DNA (ITS) and two plastid DNA regions (matK and trnLF).Fil: Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Giussani, Liliana Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Morrone, Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentin
Festuca giraldoi (Loliinae, Poaeceae), a new species from Argentina, with a revision of the taxonomic concept and identity of Festuca lilloi
No full textFestuca is a genus of the Poaceae family with about 140 species in South America. Little information is available about Festuca species growing in the Eastern Sierras Pampeanas in Argentina, a region with a significant degree of endemism. The taxonomic delimitation of some species of this region is imprecise. One such taxon is Festuca lilloi, which has not only been recognized as a native species of the Peruvian Andes or endemic to the Western Sierras Pampeanas (northern Argentina), but also as a dominant floristic element in the Eastern Sierras Pampeanas (central Argentina). In spite of its ubiquity, there is very little information on variation in its morphology, anatomy and ecology across the Sierras Pampeanas and in adjacent areas. Recent fieldwork has resulted in the finding of a new species of Festuca that was erroneously assigned to Festuca lilloi. Morphological and anatomical differences between F. lilloi and the close species are evaluated, as are the species’ ecological preferences. The delimitation of the new species, named here as Festuca giraldoi, follows the morphological species concept. A detailed description of the morphology, leaf anatomy and epidermal micromorphology (leaf and lemma) is provided for the new species.Fil: Ospina Gonzalez, Juan Camilo. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Universidad Nacional de Jujuy. Instituto de Estudios Celulares Geneticos y Moleculares.; ArgentinaFil: Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentin
Seasonal variation of plant communities and their environments along a topographic gradient in the Iberá wetland, ancient Paraná fl oodplain, Argentina
Get PDFRecently, wetlands have declined worldwide due mainly to habitat loss by human activities. In order to achieve a better understanding of the impacts that are being generated on the Iberá wetland in northeastern Argentina, the objective of this study is to analyze seasonal variation of the environments present in the sandy ridges areas of this wetland. The different environments were identifi ed and characterized according to their topography, vegetation physiognomy and dominance of species. In addition, the seasonal variation in the vegetation communities occurring in the different environments was analyzed and characterized in terms of fl oristic composition, abundance-cover and attributes. A thematic map of environments was generated and validated through the analysis of abundance-cover of the vegetation. Surveys were conducted seasonally, resulting in a total of 600 plots randomly selected. The percentage of dry matter, bare ground, vegetation-free water surface, vegetation height and depth of the water column were determined where appropriate. Six environments were identifi ed: the upland areas, the temporary ponds, the upper and lower transition zones (between aquatic and terrestrial environments), the low-lying area and the ?embalsados? (with aquaticpalustrine species). The environment classifi cation suggests that the topographic gradient and associated edaphic factors would determine the presence of the different communities. The great intra-annual variation in water regime originating from seasonal precipitation in the study area produces a variety of plant communities. The patterns of plant zonation in this wetland are changed from season to season as water levels fluctuate in space and time making the system very susceptible to changes in the hydrometric level.Fil: Corriale, Maria Jose. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biologia Experimental. Laboratorio del Grupo de Est.de Plantas Vasculares; ArgentinaFil: Di Francescantonio, Débora. Laboratorio de Ecología Forestal y Ecofisiología; . Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
In situ conservation of the wild relative of the common bean (Phaseolus vulgaris var. aborigineus) at the south of its neotropical distribution: environmental characterization of a population in central Argentina
Get PDFThe common bean (Phaseolus vulgaris L.) is a food of worldwide vital importance. Like any crop, the conservation of its wild relatives is essential to maintain the genetic variability needed for plant breeding. In situ conservation of such population has the additional benefit of generating new variations through the evolution of its natural environment. In 2004, wild populations of P. vulgaris var. aborigineus were found in the province of Córdoba (Argentina), being the southernmost specimen of its current distribution. In order to study the state and characterize the environment of such populations, vegetation censuses were conducted along a stretch of the Tanti stream-arroyo Tanti-(Punilla, Córdoba). Results showed that the wild bean has an intermediate to high constancy throughout the watercourse and its presence decreases upstream and away from the stream. Most cover took place in plots with scarce slope, high incidence of light and intense magnitude of floods. Vegetation develops in an environment surrounded by forests, meadows and intermediate physiognomy. Besides adventitious species, the studied area still has native species of high conservation value. Based on the analysis of this work, and considering the biogeographical significance of this population of wild bean, we conclude that this stretch of the studied stream is a priority area for the in situ conservation of P. vulgaris var. aborigineus.Fil: Sirolli, Horacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Drewes, Susana Ines. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kalesnik, Fabio Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Phylogenetic relationships in Opuntia (Cactaceae, Opuntioideae) from southern South America
Get PDFThe patterns of relationships between species of Opuntia from southern South America are scarcely known in spite of the importance of this region as a diversification center for the Cactaceae. This paper contributes to the better understanding of the genetic and phylogenetic relationships of 15 Opuntia species from Argentina, Bolivia, Brazil, Paraguay, and Uruguay by generating new genetic data through Inter-Simple Sequence Repeat (ISSR) genotyping and the sequencing of plastid intergenic spacers trnL-trnF and psbJ-petA. The species surveyed are: O. anacantha, O. arechavaletae, O. aurantiaca, O. bonaerensis, O. colubrina, O. discolor, O. elata, O. megapotamica, O. monacantha, O. penicilligera, O. quimilo, O. salmiana, O. schickendantzii, O. sulphurea, and O. ventanensis. The genetic distance-based analysis of 110 ISSR bands, applying the Neighbor-Joining and NeighborNet algorithms, evidenced considerable intraspecific variation in O. aurantiaca, O. elata, O. discolor, and O. salmiana. The emergent clustering pattern and the species assignment to taxonomic series show a general agreement for Armatae and Aurantiacae. The phylogenetic relationships were investigated via haplotype network and maximum likelihood approaches, within a broader sampling that involves most species currently accepted for South America, and samples from throughout the American continent. Hence, 15 haplotypes are recognized for southern South American opuntias whereas eight haplotypes are established for Northern Hemisphere opuntias. Biparentally and maternally inherited genetic data yield partially consistent results, giving genetic support for morphologically defined taxonomic series.Fil: Realini, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: González, Graciela Esther. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Font, Fabián. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Poggio, Lidia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Gottlieb, Alexandra Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin
Is prescribed fire a suitable management tool to reduce shrub encroachment in palm savannas?
No full textShrub encroachment in grasslands is a worldwide problem that has many ecological consequences, transforming previously open environments into dense forests. Disruption of natural fire regimes is one of the main causes of shrub encroachment, and the use of prescribed fire is a common strategy used to restore these ecosystems. In this study, we provide information about how a palm tree savanna under a process of shrub encroachment responds to the reintroduction of fire. We describe the effects of a first fire event on vegetation composition and structure using an experimental approach. We examine a species-specific response to the fire. After one prescribed fire event applied to four study areas of 16 ha each, we analyzed the change in vegetation physiognomy and composition in burned and control plots for 1 year. Low-intensity prescribed fire decreased height and cover of most shrub species and increased herbaceous vegetation cover over time. We classified shrub and herbaceous species response to fire according to the time they became present and their phenological characteristics. Our results can help stakeholders to determine if prescribed fire is helpful at reducing shrub encroachment in short term in similar ecosystems, considering how plant community responds to the reintroduction of fire after decades of fire suppression.Fil: Policelli, Nahuel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Ecología de Poblaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Picca, Pablo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Gomez Villafañe, Isabel Elisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentin
Exomorphological and anatomical study of the inflorescences of Southamerican Nothofagus BL. (FAGACEAE) species
Get PDFThe pistillate inflorescence of Fagaceae is surrounded and protected by a structure unique within the angiosperms: the cupule. Since last century, the lack of homologies, even among the groups more closer related to this family, has given place to a morphological approach to this structure. Historically, the small, inmature cupules and the related pistillate inflorescences have been focused on the mature, lignified and more conspicuous cupules and on the fruits protected by this kind of structures. In the present research work, it has been studied the external morphology of the staminate inflorescences and of the inmature cupules of the southamerican species of Nothofagus B1. (Fagaceae). It has also been studied the inner vascular pattern of the cupule’s valves. The purpose of this research is to get a better comprehension of the morphological nature of such interesting and enigmatic structure. An a possibleexplanation for the evolution of the cupule’s caracteristics is proposed, rlying on the different morphological variants observed in the studied species. In this way, the morphological links between Nothofagus and Trigonobalanus clearly appear confirming the close link existing between Nothofagus and the rest of the Fagaceae.Fil:Picca, Pablo Ignacio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Estudio exomorfológico y anatómico de las inflorescencias de las especies Austroamericanas del género Nothofagus BL. (Fagaceae)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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