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Search Results: 1 - 10 of 13 matches for " autoecology "
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Autoecological and Morphological Features of Astragalus stenosemioides D.F. Chamb and V.A. Matthews
Murat Ekici,Sezgin ?elik
Journal of Biological Sciences , 2005,
Abstract: Autoecological and conservation aspects of the Astragalus stenosemioides D.F. Chamb and V.A. Matthews are discussed by studying the morphological and palynological studies. A. stenosemioides is a threatened, very local endemic species to Erciyes Mountain. Erciyes Mountain (3917 m) is volcanic mountain in the inner Anatolia part of Turkey. The rocky type is andezit and volcanic tufa and the soil is andezit and tufa without limestone. For this reason Erciyes Mountain, is one of the important floristic areas in Turkey. With regards to genetic resources, this area is of major importance for in situ conservation of plant genetic diversity. The data gained from field studies were evaluated according to IUCN categories (Criteria B1 B2) and the Critically Endangered (CR) status has been proposed for the species. It was determined that it grows in three small areas in the mountain where A. stenosemioides populations are under heavy grazing stress.
Feeding habits of Thoracocharax stellatus (Characiformes: Gasteropelecidae) in the upper rio Tocantins, Brazil
Netto-Ferreira, André L.;Albrecht, Míriam P.;Nessimian, Jorge L.;Caramaschi, érica P.;
Neotropical Ichthyology , 2007, DOI: 10.1590/S1679-62252007000100009
Abstract: the silver hatchetfish thoracocharax stellatus is one of the approximately 200 fish species recorded for the upper rio tocantins, in the region where it was impounded by the serra da mesa hydroelectric dam. analysis of the stomach contents of 88 specimens revealed a diet consisting almost entirely of insects (99.6%), most of which were terrestrial (87.6%). ants, beetles, and mayflies were the main food items. dawn and dusk seemed to be the periods of highest foraging activity for t. stellatus. as a specialist on terrestrial insects, this species has a close connection with the region near the river bank, where prey is provided from the associated riparian vegetation. despite the impoundment and depletion of the land-water ecotone observed in later stages of reservoir formation, no significant changes in the diet of the few remnant specimens were recorded, which seems to indicate little feeding flexibility. thus, feeding seemed to be an overriding factor for the displacement of this species after river impoundment.
Ampliación del conocimiento sobre uso de hábitat en Liolaemus multimaculatus, sitios de fuga
Kacoliris,Federico P.; Williams,Jorge D.; Quiroga,Sofia; Molinari,Alejandro; Vicente,Natalin;
Cuadernos de herpetolog?-a , 2011,
Abstract: the knowledge about spatial preferences in animals represents the first stage to understand the interactions between the organisms and its environment. the sand dune lizard (liolaemus multimaculatus) is a species highly adapted to live in the sand. the goal of this work was to study the habitat use in different moments/situation during its period of activity, in order to obtain a more understanding about spatial preferences in this species. models based on the use vs availability criterion were applied in order to assess the preferences for sites used as refuge and to compare those sites with perch sites. the models shows differences between use and availability and also differences between perch sites and refuge sites were observed. results shows that this species used a great diversity of microhábitats with a high reject for microhabitats without vegetation cover. the conservation of good habitats for this species must consider both kinds of microhábitats, those used for thermoregulation and feed and those others used for refuge.
EFECTO DEL GRADIENTE ALTITUDINAL SOBRE ASPECTOS AUTOECOLóGICOS DE ESPELETIA PYCNOPHYLLA ssp. ANGELENSIS CUATREC. (ASTERACEAE) EN EL PáRAMO EL INFIERNILLO (NARI?O-COLOMBIA)
Benavides-Martínez,Iván F.; Burbano-Martínez,Diana L.; Urbano-Apráez,Sandra M.; Solarte-Cruz,María E.;
Actualidades Biológicas , 2007,
Abstract: some autoecological features of espeletia pycnophylla ssp. angelensis cuatrec. such as its demographic structure, population density, spatial pattern of dispersion, production of reproductive structures, adult morphometry and survivorship, were studied in an altitudinal gradient on a dry paramo of nari?o (colombia). hypothesis proposed by other authors about a linear effect caused by the elevation on these variables were completely rejected. the elevation induces an ecoclinal effect on population density, and this density correlates negatively with both production of reproductive structures and adult sizes. these results elucidate an unequivocal effect of density-dependence phenomena on population fitness. the intermediate zone of the altitudinal gradient exhibits a high population density, but on the other hand show reduced corporal adult sizes, minimal production of reproductive structures and the probability of juveniles reaching advanced ages is low. evidently, this intermediate elevation can have favorable ecological conditions for the seedling establishment, wich increments population densities at long term. we propose that other author's generalizations about the influence of elevation on the autoecology of these plants are limited, because the particular life and disturbance stories of paramos and the spatial, ecological and genetic isolating are explicative factors impossible to take away from the context. the demographic structure of the population fitted the logarithmic model, revealing its early regeneration state from the last fire event on 2003 and the similarity of the survivorship curves among every elevation, probed a high demographic stability.
Population structure of the lancelet Branchiostoma caribaeum (Cephalochordata: Branchiostomidae) in the Baía de Guanabara, Rio de Janeiro, southeastern Brazil
Silva, Luis F. B. da;Tavares, Marcos;Soares-Gomes, Abilio;
Revista Brasileira de Zoologia , 2008, DOI: 10.1590/S0101-81752008000400006
Abstract: population structure of the lancelet branchiostoma caribaeum sandevall, 1853 was studied in four surveys, corresponding to austral seasons, in a tropical bay, southeast of brazil. abundance was higher in the spring and was positively correlated to coarse sediments, limiting its occurrence to some sectors of the sampling area. body length and biomass differed seasonally but not between sexes. sexually mature individuals occurred in all seasons, suggesting continuous breeding that is typical of tropical species. variation in the frequency of small specimens indicates temporal differences in the intensity of breeding. the body length of recruits differed from other population of lancelets and the small length which b. caribaeum attained sexual maturity in guanabara bay may be related to local environmental stress or the great availability of food.
Biometry of stomata in Blechnum species (Blechnaceae) with some taxonomic and ecological implications for the ferns
Gabriel y Galán,José María; Prada,Carmen; Rolleri,Cristina H; Lahoz-Beltrá,Rafael; Martínez-Calvo,Cristina;
Revista de Biología Tropical , 2011,
Abstract: morphological stomatal traits, such as size, form and frequency, have been subject of much literature, including their relationships with environmental factors. however, little effort have focused on ferns, and very few in the genus blechnum. stomatal length, width and frequency (as stomatal index) of a number of specimens of fourteen neotropical species of blechnum were measured in adult pinnae. the aim of the work was to find biometrical relationships between stomatal traits and between stomatal traits and habit, habitat and ecosystem of the plants. statistical analyses of data were conducted using exploratory data analysis and multivariate statistical methods. stomatal length and width showed a very high correlation, suggesting an endogenous, genetic control, thus giving these traits a considerable diagnostic utility. with respect to the relationships between stomatal traits and environment, we found significant statistical relationships between altitude and stomatal index. we also addressed the interpretation of the ecological- selective significance of various assemblages of stomatal traits in a diverse conjunction of habits, habitats and ecosystems. rev. biol. trop. 59 (1): 403-415. epub 2011 march 01.
Hábitos alimentarios de las mojarras (Perciformes: Cichlidae) de la laguna Caobas, Quintana Roo, México
Valtierra-Vega,María Teresa; Schmitter-Soto,Juan Jacobo;
Revista de Biología Tropical , 2000,
Abstract: feeding habits of seven cichlid species (archocentrus octofasciatus, a. spilurus, "cichlasoma" robertsoni, "c." synspilum, "c." urophthalmus, petenia splendida, thorichthys meeki) in lake caobas, southern yucatan peninsula, were studied. samples were taken with enclosure and cast nets during the dry and rainy seasons of 1995 (day and night). the environment was characterized by measuring temperature, conductivity and ph. all individuals were below 41 mm sl (n=281). frequency of occurrence and prey abundance were analyzed. main prey items were chironomids, mites, copepods, cladocerans, and ostracods. the cichlids fed mainly on zooplankton, with the partial exceptions of p. splendida (piscivore), "c." synspilum and a. spilurus (herbivores). a cluster analysis showed that the most similar trophic spectra were those of t. meeki, "c." robertsoni and "c." salvini, which were also the least diverse. "c." synspilum and a. spilurus had an intermediate distance between their diets and those of other species. the species with the most distinctive feeding composition were p. splendida (with the most diverse and equitable diet) and the omnivore a. octofasciatus (whose diet was the richest one). t. meeki showed quantitative diel, ontogenetic, and seasonal diet changes, but none between sexes. "c." robertsoni, "c." salvini and "c." synspilum differ in food habits in caobas and in other localities, a fact that underscores the trophic adaptability of cichlids. trophic overlap between cichlids in caobas could imply absence of competition, perhaps because resources are abundant in the ecosystem.
Hábitos alimentarios de las mojarras (Perciformes: Cichlidae) de la laguna Caobas, Quintana Roo, México
María Teresa Valtierra-Vega,Juan Jacobo Schmitter-Soto
Revista de Biología Tropical , 2000,
Abstract: Se estudió la alimentación de siete especies de cíclidos (Archocentrus octofasciatus, A. spilurus, "Cichlasoma" robertsoni , "C." synspilum, "C." urophthalmus , Petenia splendida, Thorichthys meeki) en la laguna Caobas, sur de la península de Yucatán. Los muestreos se llevaron a cabo durante las estaciones seca y lluviosa de 1995. Los ejemplares medían menos de 41 mm LP. Se evaluó la frecuencia de aparición y la abundancia de las presas. Los ítemes alimentarios predominantes fueron los quironómidos, ácaros, copépodos, cladóceros y ostrácodos. La mayoría de las mojarras se mostraron zooplanctófagas, con la excepción parcial de P. splendida (piscívora), "C." synspilum y A. spilurus (herbívoras). A. octofasciatus tuvo el más amplio espectro alimentario y se consideró omnívoro. Thorichthys meeki mostró cambios cuantitativos en la dieta por hora del día, talla del pez y estación del a o, no así por sexo. Feeding habits of seven cichlid species (Archocentrus octofasciatus, A. spilurus, "Cichlasoma" robertsoni, "C." synspilum, "C." urophthalmus, Petenia splendida, Thorichthys meeki) in Lake Caobas, southern Yucatan Peninsula, were studied. Samples were taken with enclosure and cast nets during the dry and rainy seasons of 1995 (day and night). The environment was characterized by measuring temperature, conductivity and pH. All individuals were below 41 mm SL (N=281). Frequency of occurrence and prey abundance were analyzed. Main prey items were chironomids, mites, copepods, cladocerans, and ostracods. The cichlids fed mainly on zooplankton, with the partial exceptions of P. splendida (piscivore), "C." synspilum and A. spilurus (herbivores). A cluster analysis showed that the most similar trophic spectra were those of T. meeki, "C." robertsoni and "C." salvini, which were also the least diverse. "C." synspilum and A. spilurus had an intermediate distance between their diets and those of other species. The species with the most distinctive feeding composition were P. splendida (with the most diverse and equitable diet) and the omnivore A. octofasciatus (whose diet was the richest one). T. meeki showed quantitative diel, ontogenetic, and seasonal diet changes, but none between sexes. "C." robertsoni, "C." salvini and "C." synspilum differ in food habits in Caobas and in other localities, a fact that underscores the trophic adaptability of cichlids. Trophic overlap between cichlids in Caobas could imply absence of competition, perhaps because resources are abundant in the ecosystem.
Comparison of the autoecology of Quercus robur L. and Q. petraea (Mattuschka) Liebl. stands in the Northwest of the Iberian Peninsula
A. Rodriguez-Campos,I.J. Diaz-Maroto,E. Barcala-Perez,P. Vila-Lameiro
Annals of Forest Research , 2010,
Abstract: The purpose of the present work is to characterize the functioning of the ecosystems of semideciduous and deciduous Atlantic oaks in the northwest of the Iberian Peninsula. The studied species were: Quercus robur L. and Quercus petraea (Mattuschka) Liebl. To advance in the knowledge of the autecology of these species it is necessary to descend at the regional level and describe in detail the variability of the environment to determine their potential, and to decide the silvicultural treatments to be applied to preserve them and to analyze future actuations in order to a possible expansion. The analysis of the results allows knowing differences in continentalityand site conditions, with more precipitation, soil variability and humidification in Q. petraea forests respect to Q. robur. These information represent appropriate measures for the sustainable and multifunctional management of these forests, useful as indicators environmental and forestry parameters as well as the conservationstatus of these formations.
The influence of biological and environmental factors on the stable isotopic composition of ostracods – the Late Pleistocene record from Lake Albano, Central Italy
Claudio A. BELIS,Daniel ARIZTEGUI
Journal of Limnology , 2004, DOI: 10.4081/jlimnol.2004.219
Abstract: The stable oxygen and carbon isotopic composition of ostracod valves is the result of the interaction of several variables. Understanding and identifying the biological and ecological factors influencing the life of these animals improves the interpretation of isotopical data, and leads to better paleoenvironmental reconstructions. Ostracod biostratigraphy and determinations of oxygen and carbon stable isotopes on ostracod valves were carried out on a short sequence of the Last Glacial Maximum from Lake Albano (Central Italy). The oxygen isotopic composition of adults of Candona neglecta ranged between 0.5‰ and 1.5‰, and in Ilyocypris bradyi between –2‰ and –0.5‰ . Isotopic values from adults of C. neglecta fell within the range –1.5‰ to –0.8‰ when corrected for vital effect. The carbon isotopic signal ranged from 9.4‰ to 10.8‰ in adults and juveniles of C. neglecta, and from 9.8‰ to 11.3‰ in I. bradyi. Differences between left/right valve and gender were negligible, whereas there appeared to be a marked influence of life stage and species-specific factors related to vital effect and differences in microhabitat and seasonality. We combined analyses on carbon and oxygen isotopes with information deriving from ostracod ecology to reconstruct short term oscillations in past lake water level. Seasonal changes in either the temperature or the isotopic composition of the lake water were also identified. Relatively high δ18O values in ostracod valves were probably associated with the lake location and source of moisture, while high δ13C values were most probably related to the input of volcanic CO2 into the lake.
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