Use of classical bird census transects as spatial replicates for hierarchical modeling of an avian community

New monitoring programs are often designed with some form of temporal replication to deal with imperfect detection by means of occupancy models. However, classical bird census data from earlier times often lack temporal replication, precluding detection‐corrected inferences about occupancy. Historical data have a key role in many ecological studies intended to document range shifts, and so need to be made comparable with present‐day data by accounting for detection probability. We analyze a classical bird census conducted in the region of Murcia (SE Spain) in 1991 and 1992 and propose a solution to estimating detection probability for such historical data when used in a community occupancy model: the spatial replication of subplots nested within larger plots allows estimation of detection probability. In our study, the basic sample units were 1‐km transects, which were considered spatial replicates in two aggregation schemes. We fit two Bayesian multispecies occupancy models, one for each aggregation scheme, and evaluated the linear and quadratic effect of forest cover and temperature, and a linear effect of precipitation on species occupancy probabilities. Using spatial rather than temporal replicates allowed us to obtain individual species occupancy probabilities and species richness accounting for imperfect detection. Species‐specific occupancy and community size decreased with increasing annual mean temperature. Both aggregation schemes yielded estimates of occupancy and detectability that were highly correlated for each species, so in the design of future surveys ecological reasons and cost‐effective sampling designs should be considered to select the most suitable aggregation scheme. In conclusion, the use of spatial replication may often allow historical survey data to be applied formally hierarchical occupancy models and be compared with modern‐day data of the species community to analyze global change process.     

Does body size predict the buzz‐pollination frequencies used by bees?

Body size is an important trait linking pollinators and plants. Morphological matching between pollinators and plants is thought to reinforce pollinator fidelity, as the correct fit ensures that both parties benefit from the interaction. We investigated the influence of body size in a specialized pollination system (buzz‐pollination) where bees vibrate flowers to release pollen concealed within poricidal stamens. Specifically, we explored how body size influences the frequency of buzz‐pollination vibrations. Body size is expected to affect frequency as a result of the physical constraints it places on the indirect flight muscles that control the production of floral vibrations. Larger insects beat their wings less rapidly than smaller‐bodied insects when flying, but whether similar scaling relationships exist with floral vibrations has not been widely explored. This is important because the amount of pollen ejected is determined by the frequency of the vibration and the displacement of a bee's thorax. We conducted a field study in three ecogeographic regions (alpine, desert, grassland) and recorded flight and floral vibrations from freely foraging bees from 27 species across four families. We found that floral vibration frequencies were significantly higher than flight frequencies, but never exceeded 400 Hz. Also, only flight frequencies were negatively correlated with body size. As a bee's size increased, its buzz ratio (floral frequency/flight frequency) increased such that only the largest bees were capable of generating floral vibration frequencies that exceeded double that of their flight vibrations. These results indicate size affects the capacity of bees to raise floral vibration frequencies substantially above flight frequencies. This may put smaller bees at a competitive disadvantage because even at the maximum floral vibration frequency of 400 Hz, their inability to achieve comparable thoracic displacements as larger bees would result in generating vibrations with lower amplitudes, and thus less total pollen ejected for the same foraging effort.     

Biogenic synthesis of silver nanoparticles using Brazilian propolis

Biological methods have been used to synthesize silver nanoparticles through materials such as bacteria, fungi, plants, and propolis due to their reducing properties, stabilizer role and environmentally friendly characteristic. Considering the antimicrobial activity of propolis as well as the broad-spectrum antibacterial effects of silver nanoparticles, this study aim to describe the use of Brazilian propolis to synthesize silver nanoparticles (AgNP-P) and investigate its antimicrobial activity. The synthesis was optimized by factorial design, choosing the best conditions for smaller size particles. AgNP-P demonstrated a maximum absorbance at 412 nm in ultraviolet-visible spectra, which indicated a spherical format and its formation. Dynamic light scattering demonstrated a hydrodynamic size of 109 nm and polydispersity index less than 0.3, showing a good size distribution and stability. After its purification via centrifugation, microscopy analysis corroborates the format and showed the presence of propolis around silver nanoparticle. X-ray diffraction peaks were attributed to the main planes of the metallic silver crystalline structure; meanwhile infrared spectroscopy demonstrated the main groups responsible for silver reduction, represented by ∼22% of AgNP-P indicates by thermal analysis. Our product revealed an important antimicrobial activity indicating a synergism between propolis and silver nanoparticles as expected and promising to be an effective antimicrobial product to be used in infections.     

The hyolaryngeal apparatus of three species of Scinax (Scinaxinae: Hylidae: Anura) and comparison with other Hylidae species

The hyolaryngeal apparatus includes the arytenoid, cricoid and hyoid cartilages, and varied sizes and shapes can be distinguished between species. Although the larynx is an important morphological structure for sound production in frogs, few studies describe the structures and processes of its parts in hylids. We studied the hyolaryngeal anatomy of both males and females of Scinax ruber (Laurenti, 1768), using clearing and double staining methods, comparing it with that of Scinax wandae (Pyburn and Fouquette, 1971), Scinax kennedyi (Pyburn, 1973) and other hylid species. We found that S. ruber has the largest arytenoid cartilage of any species of the subfamily Scinaxinae studied to date. We described both the laryngeal differences among three Scinax species and the interspecific variability in the shapes of the projections of the arytenoid in the males of these species. The taxonomic characters (presence/absence of processes of the cartilage of Santorini, oesophageal process or bronchial processes) described here can play a key role in differentiating these species from Scinax species and from other species. In addition, we want to contribute to the natural history and comparison of the larynges in Scinax and within the genus and the Hylidae.     

Diversity of cultivable bacteria from deep-sea sediments of the Colombian Caribbean and their potential in bioremediation

The diversity of deep-sea cultivable bacteria was studied in seven sediment samples of the Colombian Caribbean. Three hundred and fifty two marine bacteria were isolated according to its distinct morphological character on the solid media, then DNA sequences of the 16S rRNA were amplified to identify the isolated strains. The identified bacterial were arranged in three phylogenetic groups, Firmicutes, Proteobacteria, and Actinobacteria, with 34 different OTUs defined at ≥?97% of similarity and 70 OTUs at ≥?98.65%, being the 51% Firmicutes, 34% Proteobacteria and 15% Actinobacteria. Bacillus and Fictibacillus were the dominant genera in Firmicutes, Halomonas and Pseudomonas in Proteobacteria and Streptomyces and Micromonospora in Actinobacteria. In addition, the strains were tested for biosurfactants and lipolytic enzymes production, with 120 biosurfactant producing strains (mainly Firmicutes) and, 56 lipolytic enzymes producing strains (Proteobacteria). This report contributes to the understanding of the diversity of the marine deep-sea cultivable bacteria from the Colombian Caribbean, and their potential application as bioremediation agents.

     

Alterations to plasma membrane lipid contents affect the biophysical properties of erythrocytes from individuals with hypertension

Genetic and environmental factors may contribute to high blood pressure, which is termed essential hypertension. Hypertension is a major independent risk factor for cardiovascular disease, stroke and renal failure; thus, elucidation of the etiopathology of hypertension merits further research. We recently reported that the platelets and neutrophils of patients with hypertension exhibit altered biophysical characteristics. In the present study, we assessed whether the major structural elements of erythrocyte plasma membranes are altered in individuals with hypertension. We compared the phospholipid (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, sphingosine) and cholesterol contents of erythrocytes from individuals with hypertension (HTN) and healthy individuals (HI) using LC/MS-MS. HTN erythrocytes contained higher phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine contents and a lower cholesterol content than HI erythrocytes. Furthermore, atomic force microscopy revealed important morphological changes in HTN erythrocytes, which reflected the increased membrane fragility and fluidity and higher levels of oxidative stress observed in HTN erythrocytes using spectrophotofluorometry, flow cytometry and spectrometry. This study reveals that alterations to the lipid contents of erythrocyte plasma membranes occur in hypertension, and these alterations in lipid composition result in morphological and physiological abnormalities that modify the dynamic properties of erythrocytes and contribute to the pathophysiology of hypertension.     

Cats under cover: Habitat models indicate a high dependency on woodlands by Atlantic Forest felids

Four Neotropical small and medium felids—the ocelot, jaguarundi, margay, and southern tiger cat—have overlapping geographic distributions in the endangered Atlantic Forest. Local studies show that these felids avoid areas with high human impact, but the three smaller ones use human‐modified areas more frequently than do ocelots. To understand how landscape changes affect the habitat distribution of these four felids in the Atlantic Forest of Argentina, we used maximum entropy models to analyze the effect of environmental and anthropogenic factors. We estimated niche breadth and overlap among these felids. The conversion of the native forest to land uses without trees was the most important variable that determined the habitat distribution of the four species. For all four species, the optimal habitat covered about 1/3 of the study area and corresponds mainly to the native forest areas. Nearly 50% of these areas had some level of protection. The niche width was higher for the small felids than for ocelots. Niche overlap was high for all species pairs, but higher among the small felids and lower for each of these with the ocelot. The four felids were negatively affected by native forest loss, with ocelots being more sensitive than the smaller felids. The conversion of unprotected forest areas to other types of land uses would imply a greater habitat loss for these felids. The protection of current remnants of Atlantic Forest in Argentina is important for the long‐term conservation of the four felids. Abstract in Spanish is available with online material.     

Inferring Cetacean Population Densities from the Absolute Dynamic Topography of the Ocean in a Hierarchical Bayesian Framework

We inferred the population densities of blue whales (Balaenoptera musculus) and short-beaked common dolphins (Delphinus delphis) in the Northeast Pacific Ocean as functions of the water-column’s physical structure by implementing hierarchical models in a Bayesian framework. This approach allowed us to propagate the uncertainty of the field observations into the inference of species-habitat relationships and to generate spatially explicit population density predictions with reduced effects of sampling heterogeneity. Our hypothesis was that the large-scale spatial distributions of these two cetacean species respond primarily to ecological processes resulting from shoaling and outcropping of the pycnocline in regions of wind-forced upwelling and eddy-like circulation. Physically, these processes affect the thermodynamic balance of the water column, decreasing its volume and thus the height of the absolute dynamic topography (ADT). Biologically, they lead to elevated primary productivity and persistent aggregation of low-trophic-level prey. Unlike other remotely sensed variables, ADT provides information about the structure of the entire water column and it is also routinely measured at high spatial-temporal resolution by satellite altimeters with uniform global coverage. Our models provide spatially explicit population density predictions for both species, even in areas where the pycnocline shoals but does not outcrop (e.g. the Costa Rica Dome and the North Equatorial Countercurrent thermocline ridge). Interannual variations in distribution during El Niño anomalies suggest that the population density of both species decreases dramatically in the Equatorial Cold Tongue and the Costa Rica Dome, and that their distributions retract to particular areas that remain productive, such as the more oceanic waters in the central California Current System, the northern Gulf of California, the North Equatorial Countercurrent thermocline ridge, and the more southern portion of the Humboldt Current System. We posit that such reductions in available foraging habitats during climatic disturbances could incur high energetic costs on these populations, ultimately affecting individual fitness and survival.