975 resultados para Taxonomic revision


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Based on data obtained at three stations in coastal waters of the Black Sea off Sevastopol in 2000 and 2001, we present seasonal dynamics of the carbon to chlorophyll a ratio in nano- and microphy-toplankton. This parameter varied approximately tenfold throughout the year. Its maximum values (442-500) were obtained in summer (July), when Pyrrophyta dominated in phytoplankton. Minimum values (36-56) were observed in winter (December),when diatomaceous species predominated. We derive a regression relating the carbon to chlorophyll a ratio to proportion of Pyrrophyta in total phytoplankton biomass, doing so separately for warm and cold seasons. Regression equations demonstrate coupled action of irradiance, temperature, and nutrient availability on the carbon to chlorophyll a ratio. For Pyrrophyta phytoplankton assemblage R**2 = 0.95, and for diatomaceous one R**2 = 0.87.

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Eocene diatom and silicoflagellate complexes from deposits of the Kronotsky Bay are presented. Pro tempore they are the most ancient finds of fossil phytoplankton with silica skeletons in the Northwest Pacific. More than 130 diatom species belonging to 59 genera and 24 silicoflagellate species belonging to 5 genera have been determined. Three Middle Eocene complexes (of the Lisitzinia kanayai, Lisitzinia inconspicua var. trilobata, and Praecymatosira monomembranaceae zones) and one presumably Middle-Late Eocene complex (of the zone with Rylandsia conniventa) of diatoms have been identified. For the first time a large silicoflagellate complex attributable to the Dictyocha hexacantha zone is presented. It is assumed that the complexes formed mainly in bathyal conditions at relatively high (close to sub-tropical) temperatures of surface waters.

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Studies of diatoms from dredge samples collected on the island slope of the Kuril-Kamchatka Trench have allowed to recognize well-preserved marine diatom assemblages corresponding to assemblages of the followed Oligocene zones: Rhizosolenia oligocaenica (subzone ''a'', 33.6-31 Ma), Cavitatus rectus (29.6-28.2 Ma), and Rocella gelida (28.2-24.0 Ma) as identified in the North Pacific zonal scale. Description of these assemblages and their complete taxonomic composition are presented. Diversity of species together with abundance and degree of preservation of diatoms and accompanying siliceous microorganisms suggests their autochtonous origin and favorable conditions of their development. Assemblages of the Early Oligocene zones Rhizosolenia oligocaenica and Cavitatus rectus recognized in sediments of the outer zone of the Lesser Kuril Ridge (submarine slope of the Shikotan Island) and on the Vityaz' submarine ridge were most probably formed under conditions of a vast shelf, while assemblage of the Late Oligocene zone Rocella gelida encountered only in the region of the Lesser Kuril Ridge formed under more deep-water conditions, presumably, over an island slope. Deepening of the basin in the region of the outer zone of the Lesser Kuril Ridge in Late Oligocene probably reflects one of stages of evolution of the Kuril-Kamchatka Trench.

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Researchers in ecology commonly use multivariate analyses (e.g. redundancy analysis, canonical correspondence analysis, Mantel correlation, multivariate analysis of variance) to interpret patterns in biological data and relate these patterns to environmental predictors. There has been, however, little recognition of the errors associated with biological data and the influence that these may have on predictions derived from ecological hypotheses. We present a permutational method that assesses the effects of taxonomic uncertainty on the multivariate analyses typically used in the analysis of ecological data. The procedure is based on iterative randomizations that randomly re-assign non identified species in each site to any of the other species found in the remaining sites. After each re-assignment of species identities, the multivariate method at stake is run and a parameter of interest is calculated. Consequently, one can estimate a range of plausible values for the parameter of interest under different scenarios of re-assigned species identities. We demonstrate the use of our approach in the calculation of two parameters with an example involving tropical tree species from western Amazonia: 1) the Mantel correlation between compositional similarity and environmental distances between pairs of sites, and; 2) the variance explained by environmental predictors in redundancy analysis (RDA). We also investigated the effects of increasing taxonomic uncertainty (i.e. number of unidentified species), and the taxonomic resolution at which morphospecies are determined (genus-resolution, family-resolution, or fully undetermined species) on the uncertainty range of these parameters. To achieve this, we performed simulations on a tree dataset from southern Mexico by randomly selecting a portion of the species contained in the dataset and classifying them as unidentified at each level of decreasing taxonomic resolution. An analysis of covariance showed that both taxonomic uncertainty and resolution significantly influence the uncertainty range of the resulting parameters. Increasing taxonomic uncertainty expands our uncertainty of the parameters estimated both in the Mantel test and RDA. The effects of increasing taxonomic resolution, however, are not as evident. The method presented in this study improves the traditional approaches to study compositional change in ecological communities by accounting for some of the uncertainty inherent to biological data. We hope that this approach can be routinely used to estimate any parameter of interest obtained from compositional data tables when faced with taxonomic uncertainty.

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EL día 24 le Junio de 1.941 me fue entregado en la secretaría de la Escuela Especial de Ingenieros de Montes el oficio que a continuación t r a n s c r i b o; rt Ministerio de cultura -Dirección General de Montes Caza y Pesca aluvial- Con esta fecha digo al Sr. Ingeniero Jefe del Distrito Forestal de Jaén lo siguiente:- Con el fin de suplir en lo posible la escasez de personal técnico afecto a ese servicio, para llevar a cabo el estudio y redacción de proyectos necesarios, este Centro ha dispuesto de acuerdo con la Dirección de la Escuela Especial de Ingenieros de Montes y teniendo en cuenta las manifestaciones de la Jefatura, designar a los alumnos del último curso Don Vicente Reus Cid, Don Juan* José Casado Bracho y Don Rafael "Fernández Huerta para que trabajen realizando los estudios que se l e encomienden a las inmediatas órdenes del Ingeniare de esa Dependencia, designado por V. S., que será quien lleve la dirección y responsabilidad del trabajo para presentarlo con una ante esa Jefatura que lo remitirá, con el regí amen t al informe a la dirección General revisiones deberán estar terminadas para fin del año corriente. Lo que traslado para su conocimiento y efectos.