Search results for "Ciencias Biológicas"
showing 10 items of 794 documents
Change in dominance determines herbivore effects on plant biodiversity
2018
Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis—that herbivore-induced changes in the competitive environment determine the response …
Reproductive inequalities in the acanthocephalan Corynosoma cetaceum: looking beyond 'crowding' effects.
2018
Background: At present, much research effort has been devoted to investigate overall (average) responses of parasite populations to specific factors, e.g., density-dependence in fecundity or mortality. However, studies on parasite populations usually pay little attention to individual variation (inequality) in reproductive success. A previous study on the acanthocephalan Corynosoma cetaceum in franciscana dolphins, Pontoporia blainvillei, revealed no overall intensity-dependent, or microhabitat effects, on mass and fecundity of worms. In this study, we investigated whether the same factors could influence mass inequalities for this species of acanthocephalan.Methods: A total of 10,138 speci…
The interplay of landscape composition and configuration: new pathways to manage functional biodiversity and agroecosystem services across Europe
2019
Managing agricultural landscapes to support biodiversity and ecosystem services is a key aim of a sustainable agriculture. However, how the spatial arrangement of crop fields and other habitats in landscapes impacts arthropods and their functions is poorly known. Synthesising data from 49 studies (1515 landscapes) across Europe, we examined effects of landscape composition (% habitats) and configuration (edge density) on arthropods in fields and their margins, pest control, pollination and yields. Configuration effects interacted with the proportions of crop and non-crop habitats, and species’ dietary, dispersal and overwintering traits led to contrasting responses to landscape variables. O…
New national and regional bryophyte records, 54
2018
Floristic and taxonnomic collaborative studies in Bryology Fil: Ellis, Leonard Thomas. The Natural History Museum, London, Uk; Reino Unido Fil: Muñoz, J.. Real Jardín Botánico de Madrid; España Fil: Suárez, G. M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina Fil: Flores, Jorge Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina
Study of a New Population of the Argentinian Endemic Species Riella choconensis Hässel (Riellaceae, Marchantiophyta) Reveals a Novel Anatomical Struc…
2019
A new population of the Argentinian endemic Riella choconensis Hässel (Riellaceae, Marchantiophyta) was discovered from a culture of sediments from the Laguna de los Juncos (Río Negro province, Argentina). This species was known previously from two nearby collections, made in 1984, in the type locality at the Ramos Mexía reservoir (Neuquén province) and was not recorded since. Fresh material from the new population enabled detailed morphological analyses, which are extensively described here, illustrated and compared to type material of the species. Based on the smooth female involucre, the species belongs to subgenus Riella Mont. However, cross-sections of this structure showed that R. cho…
Foraging behavior of two egg parasitoids exploiting chemical cues from the stink bug Piezodorus guildinii (Hemiptera: Pentatomidae).
2019
Several parasitoids attacking the same host may lead to competition. Adult parasitoids' abilities to find, parasitize and defend hosts determine resource's retention potential. In soybean, two egg parasitoid species, Telenomus podisi and Trissolcus urichi (Hymenoptera: Platygastridae), compete on the egg masses of Piezodorus guildinii (Hemiptera: Pentatomidae) one of the major pest of this crop. We evaluated parasitoid's abilities to exploit hosts' footprints; and parasitoid's behavior when competing for the same host. Both arena residence time and retention time were similar for T. podisi and T. urichi on male or female host footprints. In its turn, T. urichi reentered the area contaminate…
New national and regional bryophyte records, 43
2015
During the examination of a collection made by the authors in 2009 in San Pedro de Atacama (Antofagasta Region, Chile) one specimen was identified as Bryum incacorralis Herzog, a moss not previously known from Chile (Müller, 2009) and easily confused with some species of Philonotis Brid. (Ochi, 1980). Comparison with the type material confirmed its identity (Holotype: Bolivia, Cochabamba: an Felsen der "Estradillas" bei Incacorral, 3000 m, Herzog s.n., JE! no. 04003475). Bryum incacorralis was first described by Herzog (1909) based on material collected in Cochabamba (Bolivia), and later recorded by Griffin (1977) and O'Shea (2010) from Venezuela. It is placed in the so-called sect. "Alpini…
New national and regional bryophyte records, 36
2013
In the moss flora of Uruguay there are recorder ten species of genus Fissidens (Matteri, 2004). Three of them (F. macrobryoides, F. prionocheilos and F. vitreo-limbatus) are species incertae because the type material for the names not was located (Purssel, 2007). As part of project "Studies on Bryophytes in the Cone Sur (Systematic and Phylogeny)" some specimens recently collected in Uruguay were determinate as Fissidens asplenioides a no previously species recorded in this country. The presence of F. asplenioides in Uruguay complete the distribution range of the species in the cone Sur (is present in Argentina, Bolivia, Brazil, Chile and Paraguay). However, within the Neotropical region th…
Genetic admixture despite ecological segregation in a North African sparrow hybrid zone (Aves, Passeriformes, Passer domesticus × Passer hispaniolens…
2019
Under different environmental conditions, hybridization between the same species might result in different patterns of genetic admixture. Particularly, species pairs with large distribution ranges and long evolutionary history may have experienced several independent hybridization events over time in different zones of overlap. In birds, the diverse hybrid populations of the house sparrow (Passer domesticus) and the Spanish sparrow (Passer hispaniolensis) provide a striking example. Throughout their range of sympatry, these two species do not regularly interbreed; however, a stabilized hybrid form (Passer italiae) exists on the Italian Peninsula and on several Mediterranean islands. The spa…
The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses.
2018
Underwater visual census (UVC) is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT), designed to maximize transect length (and thus the surveyed area) with respect to diving …