Presas del búho campestre (Asio flammeus) en un agroecosistema subtropical de Paraguay

Fil: Torres Monges, Julio Cesar. Universidad Nacional de Asuncion; ParaguayFil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales; ArgentinaFil: De la Sancha, Noé U.. Chicago State University. Integrative Research Center; Estados Unidos. The Field Museum of Natural History; Estados Unido

Kinetics-Based Indirect Spectrophotometric Method for Simultaneous Determination of MnO4 (-) and Cr207 (2-): A Modern Instrumental Analysis Laboratory Experiment

Article on kinetics-based indirect spectrophotometric method for simultaneous determination of MnO4 (-) and Cr2O7 (2-) and a modern instrumental analysis laboratory experiment

Marsupiales: los mykure

Los marsupiales son mamíferos de la subclase Theria, infraclase Metatheria. Dentro de este grupo se incluyen algunas especies muy bien conocidas y carismáticas, como los canguros y koalas de Australia. Una de las particularidades de estos mamíferos es que las hembras poseen un marsupio o bolsa marsupial, que sirve para resguardar a las crías mientras estas completan su desarrollo. Sin embargo, esta estructura -que es muy evidente en algunas especies australianas- esta mayormente ausente en los marsupiales del nuevo mundo, en donde es reemplazada por ciertos pliegues de la piel. La anatomía reproductiva de las hembras también se caracteriza por la presencia de dos úteros y una vagina doble. El número de mamas varía entre especies y aún en una misma especie, con un rango entre 7 y 25. En los machos el pene es bífido, se ubica detrás del escroto y carece de hueso. Por regla general, los marsupiales invierten considerable mas tiempo en el periodo de lactación que en la gestación, en comparación con otros mamíferos.Fil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: de la Sancha, Noé U.. University of Chicago; Estados Unido

Predictive sampling effort and species-area relationship models for estimating richness in fragmented landscapes.

Loss of habitat, specifically deforestation, is a major driver of biodiversity loss. Species-area relationship (SAR) models traditionally have been used for estimating species richness, species loss as a function of habitat loss, and extrapolation of richness for given areas. Sampling-species relationships (SSRs) are interrelated yet separate drivers for species richness estimates. Traditionally, however, SAR and SSR models have been used independently and not incorporated into a single approach. We developed and compared predictive models that incorporate sampling effort species-area relationships (SESARS) along the entire Atlantic Forest of South America, and then applied the best-fit model to estimate richness in forest remnants of Interior Atlantic Forest of eastern Paraguay. This framework was applied to non-volant small mammal assemblages that reflect different tolerances to forest loss and fragmentation. In order to account for differences in functionality we estimated small mammal richness of 1) the entire non-volant small mammal assemblage, including introduced species; 2) the native species forest assemblage; and 3) the forest-specialist assemblage, with the latter two assemblages being subsets of the entire assemblage. Finally, we geospatially modeled species richness for each of the three assemblages throughout eastern Paraguay to identify remnants with high species richness. We found that multiple regression power-law interaction-term models that only included area and the interactions of area and sampling as predictors, worked best for predicting species richness for the entire assemblage and the native species forest assemblage, while several traditional SAR models (logistic, power, exponential, and ratio) best described forest-specialist richness. Species richness was significantly different between assemblages. We identified obvious remnants with high species richness in eastern Paraguay, and these remnants often were geographically isolated. We also found relatively high predicted species richness (in relation to the entire range of predicted richness values) in several geographically-isolated, medium-size forest remnants that likely have not been considered as possible priority areas for conservation. These findings highlight the importance of using an empirical dataset, created using sources representing diverse sampling efforts, to develop robust predictive models. This approach is particularly important in geographic locations where field sampling is limited yet the geographic area is experiencing rapid and dramatic land cover changes. When combined, area and sampling are powerful modeling predictors for questions of biogeography, ecology, and conservation, especially when addressing habitat loss and fragmentation

Small mammal glucocorticoid concentrations vary with forest fragment size, trap type, and mammal taxa in the Interior Atlantic Forest

Abstract Species that live in degraded habitats often show signs of physiological stress. Glucocorticoid hormones (e.g., corticosterone and cortisol) are often assessed as a proxy of the extent of physiological stress an animal has experienced. Our goal was to quantify glucocorticoids in free-ranging small mammals in fragments of Interior Atlantic Forest. We extracted glucocorticoids from fur samples of 106 small mammals (rodent genera Akodon and Oligoryzomys, and marsupial genera Gracilinanus and Marmosa) from six forest fragments (2–1200 ha) in the Reserva Natural Tapytá, Caazapá Department, Paraguay. To our knowledge, this is the first publication of corticosterone and cortisol levels for three of the four sampled genera (Akodon, Oligoryzomys, and Marmosa) in this forest system. We discovered three notable results. First, as predicted, glucocorticoid levels were higher in individuals living withing small forest fragments. Second, animals captured live using restraint trapping methods (Sherman traps) had higher glucocorticoid levels than those animals captured using kill traps (Victor traps), suggesting that hair glucocorticoid measures can reflect acute stress levels in addition to long-term glucocorticoid incorporation. These acute levels are likely due to urinary steroids diffusing into the hair shaft. This finding raises a concern about the use of certain trapping techniques in association with fur hormone analysis. Finally, as expected, we also detected genus-specific differences in glucocorticoid levels, as well as cortisol/corticosterone ratios

Discovery of a new genus record for Paraguay, the Atlantic Forest endemic rodent Abrawayaomys (Cricetidae, Sigmodontinae)

The mammals of Paraguay are still poorly known. We report a new genus for the country, Abrawayaomys, a spiny cricetid rodent endemic for the Interior Atlantic Forest. This record extends the distribution of the genus approximately 100 km, and west of the Paraná River. This addition increases the number of mammals in Paraguay to 184 and verifies that rodents are the most diverse group of mammals in the country. We outline identifying morphological characters of Abrawayaomys and elaborate on the significance of this finding for conservation and biogeography in the region.Fil: De La Sancha, Noé U.. Chicago State University; Estados Unidos. Field Museum of National History; Estados UnidosFil: Simoes Libardi, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; ArgentinaFil: Pardiñas, Ulises Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; Argentina. Instituto Nacional de Biodiversidad; Ecuado