1,721,054 research outputs found
Modeling the 20th-century distribution changes of Microgyne trifurcata, a rare plant of the southern South American grasslands
Get PDFMicrogyne trifurcata is a rare native plant species from one of the areas with the highest humanimpact on the environment in southern South America. Its habitat, mostly grasslands suitable for agriculture, has been increasingly covered by crops since the late 1800s. Microgyne trifurcata provides an excellent case study to understand how different environmental variables have affected the distribution area of a rare species. This study aims to estimate the impact of topoclimatic and land-use changes in the distribution of Microgyne trifurcata throughout the twentieth century. We carried out recent past and present distribution modeling using the Ensembles of Small Models (ESM) methodology. In this spatio-temporal study, we included climatic, topographic, and land-usevariables. We classified the occurrences into two periods of the twentieth century. The first dates from 1901 to 1940, and the second, from 1960 to 2000, when the main cropping changes of the area occurred. The projected area between 1960 and 2000 provides for this species new suitable habitats toward the northeast of the area of study. Our results highlight the importance of assessing the combined impacts of climate and land-use changes on species distributionsover time. This study shows that the potential area of Microgyne trifurcata decreased and underwent fragmentation throughout the twentieth century when these variables combined are used to model its distribution. Our outcomes prompt future studies on the vulnerability of Microgyne trifurcata to outline conservation strategies.Fil: Viera Barreto, Jessica Noelia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Sancho, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; ArgentinaFil: Bonifacino, José Mauricio. Universidad de Montevideo; UruguayFil: Pliscoff, Patricio. Pontificia Universidad Católica de Chile; Chil
Disentangling morphologically similar species of the Andean forest: Integrating results from multivariate morphometric analyses, niche modelling and climatic space comparison in Kaunia (Eupatorieae: Asteraceae)
Get PDFSix subtropical montane forest Kaunia spp. are remarkable for their superficial morphological similarity. We aim to explore different sources of data to clarify species delimitation in this complex of Kaunia. Morphological variation and environmental data of the species of the complex were assessed by using multivariate morphometric analyses. We performed a species distribution modelling approach applying BIOMOD2. Morphological quantitative traits allowed discrimination of some species in the complex. These Kaunia spp. have statistically different potential distributions, although some similarities between species in terms of climatic space were found. The species with the most similar climatic space were K. saltensis and K. lasiophthalma. The biogeographical context that could have affected the distribution of these two species is discussed. The results of our integrative study confirm the discrimination of three species, K. lasiophthalma, K. rufescens and K. saltensis, but the other three, K. arbuscularis, K. longipetiolata and K. uber, are here regarded as a single entity.Fil: Viera Barreto, Jessica Noelia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pliscoff, Patricio. Pontificia Universidad Católica de Chile; ChileFil: Donato, Mariano Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Sancho, Gisela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División de Plantas Vasculares; Argentin
Priorización de áreas para fortalecer la conservación de la flora arbórea nativa en la zona mediterránea de Chile
No full textMagíster en Ciencias Biológicas con mención en Ecología y Biología EvolutivaLos esfuerzos para la conservación de la biota terrestre siempre estarán limitados por la elección
de una muestra representativa de los elementos de la biodiversidad. Maximizar la eficiencia en la
protección se transforma entonces, en una tarea crítica debido a la dramática pérdida de
diversidad biológica que está experimentando el planeta. Debido a la imposibilidad de conservar
todas, las áreas con importancia biológica, se han desarrollado distintas metodologías para
optimizar su selección, entre éstas se encuentran los algoritmos de selección de reservas y las
metodologías de análisis GAP. En términos amplios, todas estas metodologías buscan maximizar
la cantidad de especies protegidas, por unidad de área bajo protección.
La Biogeografía Histórica ha propuesto como herramienta de selección de áreas prioritarias,
al Análisis parsimonioso de endemismos (PAE), este es un método que permite reconocer
patrones decongruencia distribucional no aleatoria entre diferentes taxa. Estos patrones entregan
información acerca de la diversidad biológica de un territorio, mediante la definición de áreas
con una alta riqueza de especies y concentración de endemismos. Se aplicó esta metodología en
la zona mediterránea de Chile ( 32° a 38° S), utilizando las 82 especies arbóreas nativas
presentes en el área. El análisis PAE definió tres bloques florísticos separados por las principales
unidades de relieve del área (Costa-Andes). Las áreas con mayor importancia para la
conservación de la biodiversidad (áreas de endemismos) se ubican en los dos extremos
latitudinales del área: la Cordillera de la Costa de las regiones de Valparaíso y Metropolitana
(33º S), y la Cordillera de Nahuelbuta (37,5º S). La distribución de los bloques florísticos y de
las áreas de endemismos tendría su explicación en el origen histórico de la biota mediterránea.
Estos resultados se relacionaron con los patrones actuales de distribución de la vegetación
nativa a través del Catastro de los recursos vegetacionales nativos, observándose que los
patrones de fragmentación y perdida de hábitat son más acentuados en los sectores costeros entre
la región de Valparaíso y del Maule. Del mismo modo se evaluó la distribución de las áreas
pertenecientes al SNASPE (Sistema Nacional de Áreas Silvestres Protegidas) en relación a las
áreas de endemismos detectadas, lo cual demostró un desbalance en las superficies protegidas.
Finalmente, se presenta un marco conceptual para complementar los resultados de la
metodología PAE, con los análisis a nivel de paisaje, con el objeto de establecer una priorización
espacial del territorio para la planificación de nuevas estrategias de conservación a nivel
regional.Conservation efforts for the conservation of the terrestrial biota will always be limited by the
selection of a representative sample of the biodiversity’s elements. Maximizing the efficiency of
biological diversity protection becomes a critical task because of the dramatic biodiversity loss
that is currently taking place. Due to the difficulty of conserving all areas of biological
importance, different methodologies have been developed to optimize their selection, some of
wich are the selection reserve algorithmsand Gap analysis. In broad terms, the objetive of these
methodologies is to maximize the quantity of protected species while minimizing the number of
protected areas.
Historical Biogeography has proposed the parsimony analysis of endemicity (PAE), wich is
a method that enables recognition of non-aleatory distribucional patterns among different taxa.
These patterns give information about the biological diversity within a territory, through the
definition of areas with high species richness and concentration endemisms. This methodology
was applied in the mediterranean area of Chile (32° to 38° S), using the 82 species of trees
present in the area. The PAE defined three floristic blocks separated by the main physiographic
units of the area (Coast-Andes). The areas with more importance for the conservation of
biodiversity (areas of endemism) are located in the two latitudinal extremes of the area: the
Coastal mountain range of the regions of Valparaíso and Metropolitan, the Coastal mountain
range of Nahuelbuta and the Andes mountain range at 37° and 38° latitude. The distribution of
the floristic blocks and the areas of endemism have their explanation in the historical formation
of the mediterranean biota.
These results were related to the current distribution patterns of the native vegetation
through the Catastro Nacional (National Cadastral) of native vegetational resources, patterns of
fragmentation and habitat loss have been observed, mainly in the coastal sectors among the
regions of Valparaíso and Maule. Additionally, the PAE results were compared with the
SNASPE (National System of Protected Wild Areas), and an inbalance in the amount of
protected area between the floristic blocks was found. Finally, a conceptual framework is
presented to complement the results of the PAE methodology, and the analyses at landscape
level, with the objective of establishing a spatial priorization in the territory for the new
conservation plannig strategies at a regional level
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
Terrestrial vertebrate baseline and analysis in six habitats present in the National Reserve Futaleufu, Palena Province, X Region, Chile
No full textModelación de la distribución de especies y ecosistemas en el tiempo y en el espacio : una revisión de las nuevas herramientas y enfoques disponibles.
No full textCambio climático: preparándonos ante lo inminente
No full textpáginas 20-24El cambio en los ensambles de especies, está produciendo transformaciones en los niveles superiores de organización de la vida, a nivel de comunidades y de composición de los ecosistemas
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
