138 research outputs found
Infrastructure features outperform environmental variables explaining rabbit abundance around motorways
Human disturbance is widespread across landscapes in the form of roads that alter wildlife populations. Knowing which road features are responsible for the species response and their relevance in comparison with environmental variables will provide useful information for effective conservation measures. We sampled relative abundance of European rabbits, a very widespread species, in motorway verges at regional scale, in an area with large variability in environmental and infrastructure conditions. Environmental variables included vegetation structure, plant productivity, distance to water sources, and altitude. Infrastructure characteristics were the type of vegetation in verges, verge width, traffic volume, and the presence of embankments. We performed a variance partitioning analysis to determine the relative importance of two sets of variables on rabbit abundance. Additionally, we identified the most important variables and their effects model averaging after model selection by AICc on hypothesis-based models. As a group, infrastructure features explained four times more variability in rabbit abundance than environmental variables, being the effects of the former critical in motorway stretches located in altered landscapes with no available habitat for rabbits, such as agricultural fields. Model selection and Akaike weights showed that verge width and traffic volume are the most important variables explaining rabbit abundance index, with positive and negative effects, respectively. In the light of these results, the response of species to the infrastructure can be modulated through the modification of motorway features, being some of them manageable in the design phase. The identification of such features leads to suggestions for improvement through low-cost corrective measures and conservation plans. As a general indication, keeping motorway verges less than 10 m wide will prevent high densities of rabbits and avoid the unwanted effects that rabbit populations can generate in some areasA.P. was supported by a PhD grant of the Basque Government. This
study forms part of the CENIT-OASIS Project funded by a consortium
of companies supported by the Centro para el Desarrollo Tecnológico
e Industrial of the Spanish Ministry of Science and Innovation
(CENIT-2008 1016). The Comunidad de Madrid, together with the
European Social Fund, supports the TEG research group through the
REMEDINAL-3 Research Network (S2013/MAE-2719
Web databases of feather photographs are useful tools for avian morphometry studies
The dataset that supports the findings of this study are archived in the Universidad Autónoma de Madrid data repository e‐cienciaDatos in https://doi.org/10.21950/ZYAOU61. Wing area, wing loading, and aspect ratio are key variables for studies of avian
comparative ecology, despite the complexity of measuring wing characteristics in
living and museum specimens. The systematic databases of feather photographs
available on the Internet may offer an alternative way of obtaining such morphometric
data. Here, we evaluate whether measurements of scanned feathers from
web photograph databases may offer reliable estimates of avian morphometry.
2. Published data on wing area were obtained for 317 bird species and feather measurements
from web photograph databases for 225 of them. A variable termed “lift
generation area,” a proxy for wing area, was calculated for each species on the
basis of the mean length of the five distal secondary feathers and wingspan data
from literature. The fit between this proposed variable and data extracted from
the literature was examined by correlation, employing linear regression to explore
the lack of fit among species.
3. “Lift generation area” proved to be highly informative as a proxy for wing area for the
study species as a whole (R2 > .98). Discrepancies observed between species were
strongly negatively associated with the size of the original sample used to calculate
wing area (p = .001) and, to a lesser extent, with bird size (p = .023), but not with
aspect ratio. It was also found that the mean value of the mismatch between “lift generation
area” and wing area (13.1%) among the study species as a whole was of similar
magnitude to that found between sources of bibliographic wing area data for the 64
species for which two published estimates of this variable were available (15.3%).
4. We conclude that measurements made from feather photograph databases are
reliable for use in studies of avian comparative ecology, enabling the inclusion of
biomechanical parameters of many more species than featured at present1. Las variables “wing area,” “wing loading” y “aspect ratio” son de gran interés en estudios
de ecología comparada de aves, si bien su medición es compleja tanto en ejemplares vivos como en especímenes de museo. Un procedimiento alternativo
para disponer de datos morfométricos de las aves puede encontrarse en las bases
de datos sistemáticas de fotografías de plumas disponibles en internet. En este trabajo
se evalúa si las mediciones de fotografías de plumas presentes en estas bases
de datos sirven para obtener estimaciones fiables de la morfometría de las aves.
2. Se recopilaron datos publicados de “wing area” para un total de 317 especies de
aves, y se pudieron obtener mediciones de plumas en atlas de plumas online de
225 de ellas. A partir de la longitud media de las 5 plumas secundarias distales y la
envergadura de las aves, extraída de la bibliografía, se calculó la variable “lift generation
area” como proxy de la “wing area” de cada especie. El ajuste de la variable
propuesta a los datos extraídos de la bibliografía se analizó mediante análisis de
correlación, explorándose por regresiones lineares las variables explicativas de la
falta de ajuste entre especies.
3. La “lift generation area” resultó muy informativa de la “wing area” para el conjunto
de las especies (R2>0.98), y las desviaciones observadas entre especies se asociaron
fuertemente al tamaño de muestra sobre la que se había calculado originalmente
la “wing area” (p = .001) y en menor medida al tamaño del ave (p = .023),
pero no al “aspect ratio.” Además, se comprobó que el valor medio del desajuste
entre “lift generation area” y “wing area” (13.1%) para el conjunto de las especies es
de la misma magnitud que la diferencia que muestran entre fuentes bibliográficas
los datos de “wing area” de las 64 especies de las que se han publicado dos estimaciones
de esta variable (15.3%).
4. Se concluye que el uso de mediciones de plumas procedentes de bases de datos de
fotografías disponibles en internet es fiable para estudios de ecología comparada
de aves, permitiendo la introducción en ellos de parámetros biomecánicos de muchas
más especies que las manejadas hasta la actualidadThis study is derived from investigations into the ecology and mortality
of birds at highspeed railways in project EU LIFE+ Impacto
Cero (LIFE 12 BIO/ES/000660). JEM and CM form part of the
REMEDINAL TE-CM research network, funded by the Comunidad de Madrid (P2018/EMT-4338)
Transport infrastructure shapes foraging habitat in a raptor community
Transport infrastructure elements are widespread and increasing in size and length in many countries, with the subsequent alteration of landscapes and wildlife communities. Nonetheless, their effects on habitat selection by raptors are still poorly understood. In this paper, we analyzed raptors ' foraging habitat selection in response to conventional roads and high capacity motorways at the landscape scale, and compared their effects with those of other variables, such as habitat structure, food availability, and presence of potential interspecific competitors. We also analyzed whether the raptors' response towards infrastructure depends on the spatial scale of observation, comparing the attraction or avoidance behavior of the species at the landscape scale with the response of individuals observed in the proximity of the infrastructure. Based on ecological hypotheses for foraging habitat selection, we built generalized linear mixed models, selected the best models according to Akaike Information Criterion and assessed variable importance by Akaike weights. At the community level, the traffic volume was the most relevant variable in the landscape for foraging habitat selection. Abundance, richness, and diversity values reached their maximum at medium traffic volumes and decreased at highest traffic volumes. Individual species showed different degrees of tolerance toward traffic, from higher abundance in areas with high traffic values to avoidance of it. Medium-sized opportunistic raptors increased their abundance near the traffic infrastructures, large scavenger raptors avoided areas with higher traffic values, and other species showed no direct response to traffic but to the presence of prey. Finally, our cross-scale analysis revealed that the effect of transport infrastructures on the behavior of some species might be detectable only at a broad scale. Also, food availability may attract raptor species to risky areas such as motorwaysAP was supported by a PhD grant of the Basque Government. This study forms part of the CENIT-OASIS Project funded by a consortium of companies supported by the Centro para el Desarrollo Tecnológico e Industrial of the Spanish Ministry of Science and Innovation (CENIT-2008 1016). The Comunidad de Madrid, together with the European Social Fund, supports the TEG research group through the REMEDINAL Research Network (S-2009/AMB/1783). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscri
Do roads alter the trophic behavior of the mesocarnivore community living close to them?
Roads have impacts on the fauna arising from habitat fragmentation, roadkill and the
barrier effect. Furthermore, roads lead species to change their activity with repercussions on predator–
prey interactions and trigger indirect effects that are currently unknown. This study analyzes
the effect of a motorway on the trophic behavior of the terrestrial carnivore community of its
surroundings. Monthly scat sampling was conducted over a year at three distances from a motorway
(0–50 m, 500–550 m and 1000–1050 m). We collected 498 scats, these originating from red fox
(39.16%), cat (24.50%), stone marten (24.09%) and badger (12.25%). The relative abundance of the
trophic resources in them was estimated together with the trophic diversity and niche overlap of the
carnivore species. The results showed a distinct effect of distance from the road on trophic behavior
of carnivores, as well as differences between species and seasons. The scats nearest the road had
10–20% more biomass of small mammals, equivalent in relative terms to a 21–48% increase in small
mammals’ biomass when compared with scats collected further from the road. This finding indicates
changes in predator–prey interactions near the road and shows that the human-generated structural
and functional changes to ecosystems spread throughout trophic networks.info:eu-repo/semantics/publishedVersio
Are motorways potential stressors of roadside wood mice (Apodemus sylvaticus) populations?
Linear infrastructures represent one of the most important human impacts on natural habitats and exert several effects on mammal populations. Motorways are recognized as a major cause of habitat fragmentation and degradation and of biodiversity loss. However, it is unknown whether motorways lead to increased physiological stress reactions in wild animal populations. We analysed faecal corticosterone metabolites (FCM) in wild populations of wood mice (Apodemus sylvaticus) living in a well-preserved Mediterranean agro-pastoral woodland at different distances (verge, 500 m and 1000 m) from the AP-51 motorway in Spain. Wood mice were captured with Sherman live traps, and fresh faecal samples from 424 individuals were collected and analyzed in the laboratory. The quantification of FCM was performed by a 5a-pregnane-3b,11b, 21-triol-20-one enzyme immunoassay. Results showed that females had higher FCM levels than males, and these levels were higher in breeding females. In addition, FCM levels were positively correlated with body weight of individuals. Wood mice captured where cattle were present showed higher FCM levels than individuals living where cattle were not detected. FCM levels were higher in non-breeding individuals living close to the motorway compared with FCM levels in those individuals captured further from the motorway. This is the first study showing evidence of the motorways' impact on physiological stress reactions in wild wood mice populations. Understanding how free-living animals are influenced by human interventions could help to understand other subtle changes observed in wild animal populations. Since mice are used world-wide as research models these results could open new perspectives testing human influence on the natural environment and trade-offs of species in degraded ecosystemsThis research has been funded by the projects: CENIT-OASIS supported by CDTI of the Spanish Ministry of Science and Innovation, REMEDINAL-2 S-2009/AMB/1783 and CCG10-UAM/AMB-5325 (Comunidad de Madrid together with the European Social Fund and Universidad Autónoma de Madrid). A. Navarro-Castilla was supported by a FPU grant from the Ministerio de Educación y Ciencia of Spai
Endozoochory by native and exotic herbivores in dry areas: consequences for germination and survival of Prosopis seeds
Mammalian herbivores can play a role in the endozoochorous dispersal of Prosopis seeds in the arid zones of Argentina, and the introduction of exotic mammals can change relevant parameters of the plant's reproductive ecology. Our specific goals were to quantify the seeds of Prosopis flexuosa, P. chilensis and P. torquata contained in the faeces of native [mara (Dolichotis patagonum), guanaco (Lama guanicoe)] and exotic [donkey (Equus asinus) and hare (Lepus europaeus)] mammals, and to determine the mortality, germination percentage and germination speed of seeds borne in faeces, compared with those collected from trees. In 2006, seeds were collected directly from trees or removed from mammal faeces. Seeds were counted and classified as apparently healthy or damaged. P. torquata and P. flexuosa seeds were found in the dung of guanaco, hare and mara, whereas only P. flexuosa seeds appeared in donkey faeces. P. chilensis seeds were only found in guanaco faeces. There was a notable relative abundance of seeds contained in small herbivore faeces in comparison to the large herbivores. The passage through the digestive tract of animals modified seed germination capacity and speed, with great variability between animal species. Guanacos had greater effects than donkeys on mortality, germination percentage and germination speed. Differences between the effects of both smaller-sized herbivores on seeds were much smaller.Fil: Campos, Claudia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Peco, Begoña. Universidad Autónoma de Madrid; EspañaFil: Campos Valeria. Universidad Nacional de San Juan; ArgentinaFil: Malo Arrázola, Juan Esteban. Universidad Autónoma de Madrid; EspañaFil: Giannoni, Stella Maris. Universidad Nacional de San Juan; ArgentinaFil: Suarez Francisco. Universidad Autónoma de Madrid; Españ
Reconciling livestock production and wild herbivore conservation: challenges and opportunities
Increasing food security and preventing further loss of biodiversity are two of humanity’s most pressing challenges. Yet, efforts to address these challenges often lead to situations of conflict between the interests of agricultural production and those of biodiversity conservation. Here, we focus on conflicts between livestock production and the conservation of wild herbivores, which have received little attention in the scientific literature. We identify four key socio-ecological challenges underlying such conflicts, which we illustrate using a range of case studies. We argue that addressing these challenges will require the implementation of co-management approaches that promote the participation of relevant stakeholders in processes of ecological monitoring, impact assessment, decision-making, and active knowledge sharing
Employment generation by small firms in Spain
Despite the relevance in terms of policy, we still know little in Spain about where and by whom jobs are created, and how that is affecting the size distribution of firms. The main innovation of this paper is to use a rich database that overcomes the problems encountered by other firm-level studies to shed some light on the employment generation of small firms in Spain. We find that small firms contribute to employment disproportionately across all sectors of the economy although the difference between their employment and job creation share is largest in the manufacturing sector. The job creators in that sector are both new and established firms whereas only new small firms outperform their larger counterparts in the service sector. The large annual job creation of the small firm size class is shifting the firm size distribution towards the very small production units, although not uniformly across industries of different technology intensit
Orientation of the Calcium Channel β Relative to the α12.2 Subunit Is Critical for Its Regulation of Channel Activity
BACKGROUND: The Ca(v)beta subunits of high voltage-activated Ca(2+) channels control the trafficking and biophysical properties of the alpha(1) subunit. The Ca(v)beta-alpha(1) interaction site has been mapped by crystallographic studies. Nevertheless, how this interaction leads to channel regulation has not been determined. One hypothesis is that betas regulate channel gating by modulating movements of IS6. A key requirement for this direct-coupling model is that the linker connecting IS6 to the alpha-interaction domain (AID) be a rigid structure. METHODOLOGY/PRINCIPAL FINDINGS: The present study tests this hypothesis by altering the flexibility and orientation of this region in alpha(1)2.2, then testing for Ca(v)beta regulation using whole cell patch clamp electrophysiology. Flexibility was induced by replacement of the middle six amino acids of the IS6-AID linker with glycine (PG6). This mutation abolished beta2a and beta3 subunits ability to shift the voltage dependence of activation and inactivation, and the ability of beta2a to produce non-inactivating currents. Orientation of Ca(v)beta with respect to alpha(1)2.2 was altered by deletion of 1, 2, or 3 amino acids from the IS6-AID linker (Bdel1, Bdel2, Bdel3, respectively). Again, the ability of Ca(v)beta subunits to regulate these biophysical properties were totally abolished in the Bdel1 and Bdel3 mutants. Functional regulation by Ca(v)beta subunits was rescued in the Bdel2 mutant, indicating that this part of the linker forms beta-sheet. The orientation of beta with respect to alpha was confirmed by the bimolecular fluorescence complementation assay. CONCLUSIONS/SIGNIFICANCE: These results show that the orientation of the Ca(v)beta subunit relative to the alpha(1)2.2 subunit is critical, and suggests additional points of contact between these subunits are required for Ca(v)beta to regulate channel activity
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