143 research outputs found
Reunion overseas: introduced wild boars and cultivated orange trees interact in the Brazilian Atlantic forest
Little is known concerning novel interactions between species that typically
interact in their native range but, as a consequence of human activity, are also interacting out of their original
distribution under new ecological conditions. Objective: We investigate the interaction between the orange tree
and wild boar, both of which share Asian origins and have been introduced to the Americas (i.e. the overseas).
Methods: Specifically, we assessed whether i) wild boars consume orange (Citrus sinensis) fruits and seeds
in orchards adjacent to a remnant of the Atlantic Forest of Brazil, ii) the orange seeds are viable after passing
through boar’s digestive tract and iii) whether the orange tree may naturalise in the forest remnant assisted by
wild boars. Results: Our camera surveys indicated that wild boar was by far the most frequent consumer of
orange fruits (40.5 % of camera trap-days). A considerable proportion of sown orange seeds extracted from fresh
boar feces emerged seedlings (27.8 %, N = 386) under controlled greenhouse conditions. Further, 37.6 % of sown
seeds (N = 500) in the forest remnant emerged seedlings in July 2015; however, after ~4 years (March 2019)
only 9 seedlings survived (i.e. 4.8 %, N = 188). Finally, 52 sweet orange seedlings were found during surveys
within the forest remnant which is intensively used by wild boars. This study indicates a high potential of boars
to act as effective seed dispersers of the sweet orange. However, harsh competition with native vegetation and
the incidence of lethal diseases, which quickly kill sweet orange trees under non-agricultural conditions, could
seriously limit orange tree establishment in the forest. Conclusions: Our results have important implications not
only because the wild boar could be a vector of potential invasive species, but also because they disperse seeds
of some native species (e.g. the queen palm, Syagrus romanzofiana) in defaunated forests, where large native
seed dispersers are missing; thus, wild boars could exert critical ecological functions lost due to human activityinfo:eu-repo/semantics/publishedVersio
Spatial isolation impacts pollinator visitation and reproductive success of a threatened self-incompatible Mediterranean tree
Pollination service is crucial to achieve successful plant sexual reproduction and long-term population persistence.
This pollination service can be affected by plant conspecific density and also by intrinsic features of individuals
related to their flowering phenology and floral display. However, studies examining intrinsic and
extrinsic traits on pollinator visitation and reproductive success of Mediterranean trees with limited reproduction
are still scarce. We analyzed the effects of plant isolation, flowering phenology, flower weight and tree size on
flower visitation probability, flowering patch visitation probability, fruit set and crop size. To this end, we
intensively monitored pollinator visitation and fruit production of 67 (in 2019) and 73 (in 2020) Pyrus bourgaeana
Decne trees within a threatened Mediterranean population. Our results revealed that isolated individuals
received more pollinators than those on conspecific aggregations, suggesting intraspecific competition for pollinators
in dense flowering neighborhoods. However, fruit set was higher in trees close to flowering conspecifics
despite having fewer visits from pollinators, suggesting pollen limitation but not pollinator limitation in spatially
isolated trees. Interestingly, we found increased crop sizes in spatially isolated trees which could be related to
reduced intraspecific competition for resources in low-density neighborhoods (water, nutrients) and/or to higher
reproductive investment (i.e. higher flower production). Overall, our results indicated pollen but not pollinator
limitation in spatially isolated trees. Under this scenario of sexual reproduction mediated by pollinators, our
findings stress the relevance of individuals’ spatial distribution for self-incompatible trees exhibiting low individuals’
densitiesinfo:eu-repo/semantics/publishedVersio
SANS study of hybrid silica aerogels under "in situ" uniaxial compression
We have modified the inorganic silica network of aerogels with polydimethylsiloxane (PDMS), a hydroxyl-terminated polymer, to obtain an organic modified silicate (ORMOSIL). Reactions were assisted by high-power ultrasounds. The resulting gels were dried under supercritical conditions of the solvent to obtain a monolithic sono-aerogel. The mechanical behaviour of these aerogels can be tuned from brittle to rubbery as a function of the organic polymer content. In order to determine the links between the mechanical behaviour and modifications made to the microstructure, SANS (small-angle neutron scattering) experiments were carried out. To measure the intensities under "in situ" uniaxial compression of the aerogel, a specific sample-holder was built. Under uniaxial compression the 2D-diagrams were significantly anisotropic (butterfly pattern), indicating the rearrangement of the polymer. The form factor of these aerogels is described well by two correlation lengths, small microporous silica clusters surrounded by entangled polymer chains of 6 nm average size (blobs), which form a larger secondary level of agglomerates governed by the "frozen-in" elastic constraints.Comisión Interministerial de Ciencia y TecnologÃa MAT2005-1583European Commission CT-2003-50592
Interspecific interactions among functionally diverse frugivores and their outcomes for plant reproduction: a new approach based on camera-trap data and tailored null models
Research ArticleThe study of plant-frugivore interactions is essential to understand the ecology and evolution
of many plant communities. However, very little is known about how interactions among frugivores
indirectly affect plant reproductive success. In this study, we examined direct interactions
among vertebrate frugivores sharing the same fruit resources. Then, we inferred
how the revealed direct interspecific interactions could lead to indirect (positive or negative)
effects on reproductive success of fleshy fruited plants. To do so, we developed a new analytical
approach that combines camera trap data (spatial location, visitor species, date and
time, activity) and tailored null models that allowed us to infer spatial-temporal interactions
(attraction, avoidance or indifference) between pairs of frugivore species. To illustrate our
approach, we chose to study the system composed by the Mediterranean dwarf palm, Chamaerops
humilis, the Iberian pear tree, Pyrus bourgaeana, and their shared functionally
diverse assemblages of vertebrate frugivores in a Mediterranean area of SW Spain. We first
assessed the extent to which different pairs of frugivore species tend to visit the same or different
fruiting individual plants. Then, for pairs of species that used the same individual
plants, we evaluated their spatial-temporal relationship. Our first step showed, for instance,
that some prey frugivore species (e.g. lagomorphs) tend to avoid those C. humilis individuals
that were most visited by their predators (e.g. red foxes). Also, the second step revealed
temporal attraction between large wild and domestic frugivore ungulates (e.g. red deer,
cows) and medium-sized frugivores (e.g. red foxes) suggesting that large mammals could
facilitate the C. humilis and P. bourgaeana exploitation to other smaller frugivores by making
fruits more easily accessible. Finally, our results allowed us to identify direct interaction pathways,
that revealed how the mutualistic and antagonistic relations between animal associates
derived into indirect effects on both plants seed dispersal success. For instance, we
found that large-sized seed predators (e.g. ungulates) had a direct positive effect on the likelihood
of visits by legitimate seed dispersers (e.g. red foxes) to both fleshy fruited plants.
Then, seed predators showed an indirect positive effect on the plants’ reproductive Our new analytical approach provides a widely applicable framework for further studies on
multispecies interactions in different systems beyond plant-frugivore interactions, including
plant-pollinator interactions, the exploitation of plants by herbivores, and the use of carcasses
by vertebrate scavengersinfo:eu-repo/semantics/publishedVersio
Bioactivity of wollastonite/aerogels composites obtained from a TEOS-MTES matrix
Organic-inorganic hybrid materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS), methyltrimethoxysilane (MTES), synthetic wollastonite powders and polydimethylsiloxane (PDMS) in an ethanol solution. Aerogels were prepared from acid hydrolysis of TEOS and MTES with different volume ratio in ethanol, followed by addition of wollastonite powder and PDMS in order to obtain aerogels with 20 wt% of PDMS and 5 wt% of CaO of the total silica. Finally, when the wet gels were obtained, they were supercritically dried at 260°C and 90 bar, in ethanol. In order to obtain its bioactivity, one method for surface activation is based on a wet chemical alkaline treatment. The particular interest of this study is that we introduce hybrid aerogels, in a 1 M solution of NaOH, for 30 s at room temperature. We evaluate the bioactivity of TEOS-MTES aerogel when immersed in a static volume of simulated body fluid (SBF). An apatite layer of spherical-shaped particles of uniform size smaller than 5 microns is observed to form on the surface of the aerogels after 25 days soaking in SBF.Ministerio de Ciencia e Innovación MAT2005-01583Junta de AndalucÃa TEP 79
FrugivorÃa y dispersión de semillas por mamÃferos carnÃvoros: rasgos funcionales
Muchas especies de mamÃferos carnÃvoros (Orden Carnivora) consumen frutos carnosos, transportan semillas en sus tractos digestivos y las defecan
sin dañarlas en condiciones apropiadas para la germinación. En este artÃculo, revisamos el conocimiento adquirido sobre este mutualismo en las
últimas tres décadas, desde que tres trabajos pioneros revelaron la importancia de los carnÃvoros como dispersores de semillas en ecosistemas
templados. Nos centramos en los rasgos funcionales de los carnÃvoros consumiendo frutos y diseminando semillas, haciendo especial énfasis en
sus diferencias con las aves, el principal grupo de vertebrados frugÃvoros en ecosistemas templados. Los carnÃvoros no están sujetos a las restricciones
fenológicas o morfológicas que tÃpicamente limitan el consumo de determinados frutos en muchas especies de aves. Consumen preferentemente
frutos cuyos atributos son compartidos con muchas especies de frutos cultivados por el hombre, lo que explica el consumo frecuente de
éstos en paisajes antrópicos. Sus amplios requerimientos espaciales favorecen la dispersión de semillas a larga distancia, mientras que su generalismo
en relación al hábitat favorece el flujo de semillas entre hábitats contrastados. De este modo, los carnÃvoros promueven la conectividad
entre poblaciones vegetales y la colonización. Estas funciones ecológicas son clave para las comunidades vegetales nativas, especialmente en escenarios
de cambios de uso de suelo. Sin embargo, estos patrones de dispersión de semillas pueden contribuir a la invasión de plantas exóticas.
Aún ignoramos en gran medida el papel de los carnÃvoros en términos cuantitativos de la dispersión de semillas y las diferencias funcionales entre
especies dentro del gremio. La integración de muestreos clásicos e innovadoras técnicas moleculares y de análisis espacial promete aportar conocimiento
inédito en estas cuestiones[EN ] Many species of carnivorous mammals (Order Carnivora) consume fleshy fruits, transport seeds in their digestive tracts, and defecate them without
damage in conditions that are suitable for germination. In this article, we review the state of the art on this mutualism in the past three decades, since
three pioneering studies revealed the importance of carnivores as seed dispersers in temperate ecosystems. We focus on the functional traits of carnivores
consuming fruits and disseminating seeds, with particular emphasis on their differences with birds, the main group of vertebrate frugivores
in temperate ecosystems. Carnivores are not subject to the phenological or morphological constraints that typically limit the consumption of certain
fruit species in many bird species. They preferably consume fruits whose traits are shared with many fruit species cultivated by man, which explains
the frequent consumption of cultivated fruits in anthropogenic landscapes. The large spatial requirements of carnivores promote long-distance seed
dispersal, while their habitat generalism promotes seed flows between contrasting habitats. Thus, carnivores promote connectivity between plant
populations and colonization. These are key ecological functions for native plant communities, especially in scenarios of land-use changes. However,
these seed dispersal patterns can contribute to the invasion of exotic plants. We still largely ignore the role of carnivores in quantitative terms of seed
dispersal and the functional differences between species within the guild. Integrating traditional fieldwork and innovative molecular techniques and
spatial analysis promises to provide unprecedented knowledge on these issuesPeer reviewe
Radio outburst from a massive (proto)star. II. A portrait in space and time of the expanding radio jet from S255 NIRS3
Observations indicate that the accretion process in star formation may occur
through accretion outbursts. This phenomenon has also now been detected in a
few young massive (proto)stars (>8 Msun). The recent outburst at radio
wavelengths of the massive (proto)star S255 NIRS3 has been interpreted by us as
expansion of a thermal jet, fed by the infalling material. To follow up on our
previous study and confirm our interpretation, we monitored the source for more
than 1 yr in six bands from 1.5 GHz to 45.5 GHz and, after ~1.5 yr, with the
Atacama Large Millimeter/submillimeter Array at two epochs, which made it
possible to detect the proper motions of the jet lobes. The prediction of our
previous study is confirmed by the new results. The radio jet is found to
expand, while the flux, after an initial exponential increase, appears to
stabilise and eventually decline. The radio flux measured during our monitoring
is attributed to a single NE lobe, However, from 2019 a second lobe has been
emerging to the SW, probably powered by the same accretion outburst, although
with a delay of at least a couple of years. Flux densities at >6 GHz were
satisfactorily fitted with a jet model, whereas those below 6 GHz are clearly
underestimated by the model. This indicates that non-thermal emission becomes
dominant at long wavelengths. Our results suggest that thermal jets can be a
direct consequence of accretion events, when yearly flux variations are
detected. The end of the accretion outburst is mirrored in the radio jet, as ~1
yr after the onset of the radio outburst, the inner radius of the jet began to
increase while the jet mass stopped growing, as expected if the powering
mechanism of the jet is quenched. Our findings support a tight connection
between accretion and ejection in massive stars, consistent with a formation
process involving a disk-jet system similar to that of low-mass stars
The sharpest view on the high-mass star-forming region S255IR. Near-InfraRed Adaptive Optics Imaging on the Outbursting Source NIRS3
Massive stars have an impact on their surroundings from early in their
formation until the end of their lives. However, very little is known about
their formation. Episodic accretion may play a crucial role, but observations
of these events have only been reported towards a handful of massive
protostars. We aim to investigate the outburst event from the high-mass
star-forming region S255IR where recently the protostar NIRS3 underwent an
accretion outburst. We follow the evolution of this source both in photometry
and morphology of its surroundings. Methods: We perform near-infrared adaptive
optics observations on the S255IR central region using the Large Binocular
Telescope in the K broad-band and the H and Br
narrow-band filters with an angular resolution of \sim0\farcs06, close to the
diffraction limit. We discover a new near-infrared knot north-east from NIRS3
that we interpret as a jet knot that was ejected during the last accretion
outburst and observed in the radio regime as part of a follow-up after the
outburst. We measure a mean tangential velocity for this knot of
. We analyse the continuum-subtracted images
from H which traces jet shocked emission, and Br which traces
scattered light from a combination of accretion activity and UV radiation from
the central massive protostar. We observe a significant decrease in flux at the
location of NIRS3, with K=13.48\,mag being the absolute minimum in the historic
series. Our observations strongly suggest a scenario where the episodic
accretion is followed by an episodic ejection response in the near-infrared, as
it was seen in the earlier radio follow-up. The 30 years of
photometry suggests that NIRS3 might have undergone another outburst in the
late 1980s, being the first massive protostar with such evidence observed in
the near-infrared.Comment: Accepted for publication in Astronomy and Astrophysics. 10 pages, 8
figure
Phosphogypsum waste lime as a promising substitute of commercial limes: A rheological approach
This paper presents the rheological properties of three types of lime putty, specifying the influence of their origin. The study aims to compare a special lime putty prepared from phosphogypsum with a commercial lime powder and an aged lime putty. The results obtained in terms of chemical composition, crystalline structure, grain size and rheological characterization, (linear viscoelasticity, shear rate and time-dependent flow behaviour) are presented in the study. Putties studied present a similar rheological response, which mainly depends on the particle size and water content. Lower values of the linear viscoelastic functions and viscosity were found for the phosphogypsum lime putty, in agreement with the higher particle size. Transient flow tests reveal a predominant elastic response with no significant shear-induced structural perturbations. However, either a thickening phenomenon over time, i.e. rheopexy, favoured at low shear rates, or a viscosity decrease, i.e. thixotropy, favoured at high shear rates, was observed
Deuterium Fractionation across the Infrared Dark Cloud G034.77-00.55 interacting with the Supernova Remnant W44
Supernova remnants (SNRs) may regulate star formation in galaxies. For
example, SNR-driven shocks may form new molecular gas or compress pre-existing
clouds and trigger the formation of new stars. To test this scenario, we
measure the deuteration of , , a well-studied tracer
of pre-stellar cores, across the Infrared Dark Cloud (IRDC) G034.77-00.55,
known to be experiencing a shock interaction with the SNR W44. We use
NH and ND J=1-0 single pointing observations obtained with the
30m antenna at the Instituto de Radioastronomia Millimetrica to infer
toward five positions across the cloud, namely a massive
core, different regions across the shock front, a dense clump and ambient gas.
We find in the range 0.03-0.1, several orders of magnitude
larger than the cosmic D/H ratio (10). Across the shock front,
is enhanced by more than a factor of 2
(0.05-0.07) with respect to the ambient gas (0.03)
and similar to that measured generally in pre-stellar cores. Indeed, in the
massive core and dense clump regions of this IRDC we measure
}0.1. We find enhanced deuteration of across
the region of the shock, at a level that is enhanced with respect to regions of
unperturbed gas. It is possible that this has been induced by shock
compression, which would then be indirect evidence that the shock is triggering
conditions for future star formation. However, since unperturbed dense regions
also show elevated levels of deuteration, further, higher-resolution studies
are needed to better understand the structure and kinematics of the deuterated
material in the shock region, e.g., if it still in relatively diffuse form or
already organised in a population of low-mass pre-stellar cores.Comment: Accepted for publication on A&A; 8 pages, 5 figure
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