1,032 research outputs found
Hyaenids, felids and canids as bone accumulators: Does the natural history of extant species support zooarchaeological inferences?
Mammalian carnivores may be important agents of prehistoric bone accumulations. Taphonomic analyses
of bone assemblages used for specific assignment usually include information on feeding, breeding,
denning and even defecating ecology of extant species. Here, we review literature for the Hyaenidae,
Felidae and Canidae families of carnivores, focusing on the ecological and behavioural traits that are
commonly used as criteria to assign bone accumulations to specific carnivores, and whether these
correspond to the present behaviour and ecology of extant species. We found a total of 93 records where
12 species (9 extant species) of these families were considered as bone accumulators in archaeozoological
sites. Hyaenidae was the group most often cited, followed by Felidae and Canidae. Crocuta
crocuta was by far the species most often cited as a bone accumulator. Most bone deposits assigned to
carnivores (84.9%) were found in underground cavities, and to a lesser extent in non-cave deposits
(15.1%). The use assigned to the sites was mainly as a den (29.5%) or breeding den (29.5%), followed by
prey depot (16.2%), feeding shelter (12.4%), and to a lesser extent a hunting place (7.6%), with some
remarkable differences among families. Coprolites were also found in 53.8% of cases.
The behaviour of present hyenas may be similar to that of prehistoric ones as they commonly use
underground dens, defecate inside of them and frequently accumulate prey remains. On the other hand,
even though present canids are more often recorded than felids using underground dens and accumulating
prey, the latter are more often recorded as prehistoric bone accumulators than the former. The
behaviour of only one present species of canid (V. vulpes) and other a felid (P. pardus) matches the one
presumed for prehistoric individuals of such species in relation to bone and scat accumulation. The role
of the remaining species as bone and scat accumulator agents in prehistoric sites remains questionable
due to differences in their present behaviour. Therefore, many assignments of bone accumulation to
specific carnivores are based on assumptions, which did not coincide with the present natural history of
the species. Our review also highlights the absence of records of small species as prehistoric bone
accumulators.We thank Cuauhtemoc Ch avez and Ana Carolina Srbek for their
unpublished information on jaguars. HRV is a beneficiary of a PhD
scholarship “Severo Ochoa” from the Regional Government of
Principality of Asturias, and AMG was supported by the Predoctoral
Fellowship PRE2018-086102
The influence of road networks on brown bear spatial distribution and habitat suitability in a human-modified landscape
Roads are human infrastructure that heavily affect wildlife, often with marked
impacts on carnivores, including brown bears Ursus arctos. Here, we assessed the
potential impact of road networks on the distribution of brown bears in the small, isolated
and endangered Cantabrian population of north-western Spain. To ascertain
whether local road networks affect brown bear spatial distribution, we first assessed
potential influences on the distance of bear locations to roads using candidate models
which included topographic variables, landcover types, bear age and reproductive status,
traffic volume and road visibility. Then, we built two sets of habitat suitability
models, both with and without roads, to discern the possible loss of habitat suitability
caused by roads. The mean distance of bear locations to the nearest road was
968 804 m and the closest road was a low traffic road in 72.5% of cases. Candidate
models showed little influence of our variables on bear distance to the nearest
road, with the exception of elevation. Habitat suitability models revealed that road
networks in our study area seem to have almost no effect on brown bear habitat suitability,
except for females with yearlings during the denning season. However, this
result may also be a consequence of the fact that only a small proportion (16.5%) of
the cells classified as suitable bear habitats were crossed by roads, that is, most of the
roads are primarily located in unsuitable bear habitats in the Cantabrian Mountains.
Compared to previous studies conducted in other populations, mainly North American
ones, our findings might suggest a different response of Eurasian brown bears to
roads due to a longer bear-human coexistence in Europe versus North America. However,
the indirect approach used in our study does not exclude other detrimental
effects, for example, road mortality, increased stress and movement pattern disruption,
only detectable by more direct approaches such as telemetry
Cosmogenic production of tritium in dark matter detectors
The direct detection of dark matter particles requires ultra-low background conditions at energies below a few tens of keV. Radioactive isotopes are produced via cosmogenic activation in detectors and other materials and those isotopes constitute a background source which has to be under control. In particular, tritium is specially relevant due to its decay properties (very low endpoint energy and long half-life) when induced in the detector medium, and because it can be generated in any material as a spallation product. Quantification of cosmogenic production of tritium is not straightforward, neither experimentally nor by calculations. In this work, a method for the calculation of production rates at sea level has been developed and applied to some of the materials typically used as targets in dark matter detectors (germanium, sodium iodide, argon and neon); it is based on a selected description of tritium production cross sections over the entire energy range of cosmic nucleons. Results have been compared to available data in the literature, either based on other calculations or from measurements. The obtained tritium production rates, ranging from a few tens to a few hundreds of nuclei per kg and per day at sea level, point to a significant contribution to the background in dark matter experiments, requiring the application of specific protocols for target material purification, material storing underground and limiting the time the detector is on surface during the building process in order to minimize the exposure to the most dangerous cosmic ray components
Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)
This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and
Technology (CICYT), the
Spanish National Parks agency, the European Commission, the
Spanish Ministry of Science, and the European
Social Fund
Revealing the last 13,500 years of environmental history from the multiproxy record of a mountain lake (Lago Enol, northern Iberian Peninsula)
This is the author's accepted manuscript. The final publication is available at Springer via http://dx.doi.org/10.1007/s10933-009-9387-7.We present the Holocene sequence from Lago Enol (43°16′N, 4°59′W, 1,070 m a.s.l.), Cantabrian Mountains, northern Spain. A multiproxy analysis provided comprehensive information about regional humidity and temperature changes. The analysis included sedimentological descriptions, physical properties, organic carbon and carbonate content, mineralogy and geochemical composition together with biological proxies including diatom and ostracod assemblages. A detailed pollen study enabled reconstruction of variations in vegetation cover, which were interpreted in the context of climate changes and human impact. Four distinct stages were recognized for the last 13,500 years: (1) a cold and dry episode that includes the Younger Dryas event (13,500–11,600 cal. year BP); (2) a humid and warmer period characterizing the onset of the Holocene (11,600–8,700 cal. year BP); (3) a tendency toward a drier climate during the middle Holocene (8,700–4,650 cal. year BP); and (4) a return to humid conditions following landscape modification by human activity (pastoral activities, deforestation) in the late Holocene (4,650–2,200 cal. year BP). Superimposed on relatively stable landscape conditions (e.g. maintenance of well established forests), the typical environmental variability of the southern European region is observed at this site.The Spanish Inter-Ministry Commission of Science and
Technology (CICYT), the
Spanish National Parks agency, the European Commission, the
Spanish Ministry of Science, and the European
Social Fund
The influence of road networks on brown bear spatial distribution and habitat suitability in a human-modified landscape
Roads are human infrastructure that heavily affect wildlife, often with marked impacts on carnivores, including brown bears Ursus arctos. Here, we assessed the potential impact of road networks on the distribution of brown bears in the small, isolated and endangered Cantabrian population of north-western Spain. To ascertain whether local road networks affect brown bear spatial distribution, we first assessed potential influences on the distance of bear locations to roads using candidate models which included topographic variables, landcover types, bear age and reproductive status, traffic volume and road visibility. Then, we built two sets of habitat suitability models, both with and without roads, to discern the possible loss of habitat suitability caused by roads. The mean distance of bear locations to the nearest road was 968 ± 804 m and the closest road was a low traffic road in 72.5% of cases. Candidate models showed little influence of our variables on bear distance to the nearest road, with the exception of elevation. Habitat suitability models revealed that road networks in our study area seem to have almost no effect on brown bear habitat suitability, except for females with yearlings during the denning season. However, this result may also be a consequence of the fact that only a small proportion (16.5%) of the cells classified as suitable bear habitats were crossed by roads, that is, most of the roads are primarily located in unsuitable bear habitats in the Cantabrian Mountains. Compared to previous studies conducted in other populations, mainly North American ones, our findings might suggest a different response of Eurasian brown bears to roads due to a longer bear-human coexistence in Europe versus North America. However, the indirect approach used in our study does not exclude other detrimental effects, for example, road mortality, increased stress and movement pattern disruption, only detectable by more direct approaches such as telemetry.During this research, EG-B was financially supported by a FPU grant (FPU15-03429) from the Spanish Ministry of Science, Innovation and Universities. VP, EG-B, AMG and HRV were financially supported by the I + D + I Project PID2020-114181GB-I00 financed by the Spanish Ministry of Science and Innovation, the Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, EU). AMG was supported by the Predoctoral Fellowship PRE2018-086102. AZA was financially supported by a Margarita Salas contract financed by the European Union-NextGenerationEU, Ministerio de Universidades y Plan de Recuperación, Transformación y Resiliencia, through the call of the Universidad de Oviedo (Asturias).Peer reviewe
Gas exchange at whole plant level shows that a less conservative water use is linked to a higher performance in three ecologically distinct pine species
Increasing temperatures and decreasing precipitation in large areas of the planet as a consequence of
global warming will affect plant growth and survival. However, the impact of climatic conditions will
differ across species depending on their stomatal response to increasing aridity, as this will ultimately
affect the balance between carbon assimilation and water loss. In this study, we monitored gas
exchange, growth and survival in saplings of three widely distributed European pine species (Pinus
halepensis, P. nigra and P. sylvestris) with contrasting distribution and ecological requirements in
order to ascertain the relationship between stomatal control and plant performance. The experiment
was conducted in a common garden environment resembling rainfall and temperature conditions
that two of the three species are expected to encounter in the near future. In addition, gas exchange
was monitored both at the leaf and at the whole-plant level using a transient-state closed chamber,
which allowed us to model the response of the whole plant to increased air evaporative demand
(AED). P. sylvestris was the species with lowest survival and performance. By contrast, P. halepensis
showed no mortality, much higher growth (two orders of magnitude), carbon assimilation (ca. 14
fold higher) and stomatal conductance and water transpiration (ca. 4 fold higher) than the other two
species. As a consequence, P. halepensis exhibited higher values of water-use efficiency than the rest of
the species even at the highest values of AED. Overall, the results strongly support that the weaker
stomatal control of P. halepensis, which is linked to lower stem water potential, enabled this species to
maximize carbon uptake under drought stress and ultimately outperform the more water
conservative P. nigra and P. sylvestris. These results suggest that under a hotter drought scenario
P. nigra and P. sylvestris would very likely suffer increased mortality, whereas P. halepensis could
maintain gas exchange and avoid water-induced growth limitation. This might ultimately foster an
expansion of P. halepensis to higher latitudes and elevations.This work was supported by the projects ECOLPIN
(AGL2011–24296) and Remedinal 3 (S2013/ MAE-
2719) of the Madrid Government, by a FPU fellowship
from the Spanish Ministry of Education, Culture
and Sport (FPU13/03410) to DS and by EU Marie
Curie (FP7–2013-IOF-625988) fellowship to EPSC
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