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  • 1
    Publication Date: 2014-10-01
    Description: Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context. # doi:10.1890/13-1416.1
    Print ISSN: 1051-0761
    Electronic ISSN: 1939-5582
    Topics: Biology
    Published by Wiley on behalf of The Ecological Society of America (ESA).
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  • 2
    Publication Date: 2016-01-08
    Description: In the spring of 2014, an onshore–offshore geophysical experiment ("Crustal Characterization of the Rivera plate–Jalisco Block Boundary and Its Implications for Seismic and Tsunami Hazard Assessment") was carried out in the frame of the TsuJal project to define the crustal architecture of the western Mexican active margin and identify potential structural sources that can trigger earthquakes and tsunamis at the convergence between the Rivera plate (RP) and the Jalisco Block (JB) within the North American plate. In this work, we present the preliminary results about bathymetric, structural geology, and wide-angle seismic data of the southern coast of Bahía de Banderas. These data indicate the slab thickness in this area is about 10 km and presents a dip angle of about 8°. Continental crustal thickness below Puerto Vallarta is about 20 km, but no evidences of continental Moho and clear subduction features (trench, accretionary prism) are observed. Nevertheless, this model supports the hypothesis that the region of Bahía de Banderas is under strong crustal stresses generating structural lineaments with the same trends offshore and inland due to the convergence of the RP against the JB. Most of the seismicity reported can be associated with the main structural lineaments. Moreover, the Banderas Canyon (BC) is apparently in an eastward opening process, which seems to continue through the Rio Pitillal river valley; no seismic or morphological evidences were found to suggest the BC is a continuation of the Vallarta graben. Offshore, the Sierra de Cleofas, located south of María Cleofas Island, marks the limit between the RP and the JB along 100 km. It may be the result of the RP pushing against the JB establishing the beginning of the current subduction process, with associated seismic activity. If a subduction type earthquake occurs in this area, the associated magnitude will be about 7.5 and could have a tsunamigenic effect.
    Print ISSN: 0895-0695
    Electronic ISSN: 1938-2057
    Topics: Geosciences
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  • 3
    Publication Date: 2015-02-11
    Description: Activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) underlie the pathogenesis and chemoresistance of ∼30% of all human tumors, yet the development of high-affinity inhibitors that target the broad range of KRAS mutants remains a formidable challenge. Here, we report the development and validation of stabilized alpha...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 4
    Publication Date: 2012-09-08
    Description: Questions What is the relative importance of direct herbivory compared to microsite modification in ungulate impacts on secondary forest succession? Do domestic ungulate impacts differ between small-seeded pioneers and large-seeded late successional species? Location Birch–beech secondary forest ( Betula celtiberica and Fagus sylvatica ), Bizkaia, Northern Spain. Methods We conducted a detailed spatial analysis of 216 permanent 1-m 2 subplots that were distributed among six plots, of which three were fenced (each plot was 3600-m 2 ) and three were unfenced (each plot was 1296-m 2 ). Within each subplot, the emergence and survival rates of all tree, shrub and vine species were monitored. In total, 21 censuses of the subplots were conducted across 4 yr (1998–2001). Ungulate abundance was measured by using the pellet counting method. Structural equation models were applied to model the entire recruitment process. Results Emergence and survival rates differed between small- and large-seeded species, and the effect of domestic ungulates (primarily sheep) on these rates depended on seed traits. Sheep did not affect the emergence of large-seeded species (e.g. beech and ivy), but did result in a decline in their survival. In contrast, the emergence of small-seeded species (e.g. birch) was promoted through an increase in bare soil cover because of trampling by the ungulates, but no significant effect on survival was observed. Interestingly, the sheep prompted differences in the role of the understorey vegetation: the understorey composition was able to promote the survival of large-seeded species growing in unfenced conditions by reducing the risk of herbivore predation, but had a negative effect on the survival of small-seeded species because of low light availability under the shaded shrub canopies. Conclusions Our results clearly highlight that sheep can change the seedling bank structure in a secondary temperate forest, thereby affecting the dynamics and structure of forest remnants. This impact should be included as a critical driver in current predictive models of forest dynamics in temperate regions, since herbivore pressure is increasing in forests across Europe due to an increase in wild ungulate populations and livestock. Land abandonment is leading to secondary succession in large areas of Europe. Simultaneously, herbivore pressure is increasing in some places due to sharp changes in management practices. Differential response to herbivory between early and late succesional species may alter forest dynamics. Sheep trampling increases seedling establishment of early successional species, while late successional species are negatively affected by browsing.
    Print ISSN: 1100-9233
    Electronic ISSN: 1654-1103
    Topics: Biology
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  • 5
    Publication Date: 2011-07-01
    Description: We analyze substitution tiling spaces with fivefold symmetry. In the substitution process, the introduction of randomness can be done by means of two methods which may be combined: composition of inflation rules for a given prototile set and tile rearrangements. The configurational entropy of the random substitution process is computed in the case of prototile subdivision followed by tile rearrangement. When aperiodic tilings are studied from the point of view of dynamical systems, rather than treating a single one, a collection of them is considered. Tiling spaces are defined for deterministic substitutions, which can be seen as the set of tilings that locally look like translates of a given tiling. Čech cohomology groups are the simplest topological invariants of such spaces. The cohomologies of two deterministic pentagonal tiling spaces are studied.
    Print ISSN: 1026-0226
    Electronic ISSN: 1607-887X
    Topics: Mathematics
    Published by Hindawi
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  • 6
    Publication Date: 2013-11-01
    Description: The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Delgado-Baquerizo, Manuel -- Maestre, Fernando T -- Gallardo, Antonio -- Bowker, Matthew A -- Wallenstein, Matthew D -- Quero, Jose Luis -- Ochoa, Victoria -- Gozalo, Beatriz -- Garcia-Gomez, Miguel -- Soliveres, Santiago -- Garcia-Palacios, Pablo -- Berdugo, Miguel -- Valencia, Enrique -- Escolar, Cristina -- Arredondo, Tulio -- Barraza-Zepeda, Claudia -- Bran, Donaldo -- Carreira, Jose Antonio -- Chaieb, Mohamed -- Conceicao, Abel A -- Derak, Mchich -- Eldridge, David J -- Escudero, Adrian -- Espinosa, Carlos I -- Gaitan, Juan -- Gatica, M Gabriel -- Gomez-Gonzalez, Susana -- Guzman, Elizabeth -- Gutierrez, Julio R -- Florentino, Adriana -- Hepper, Estela -- Hernandez, Rosa M -- Huber-Sannwald, Elisabeth -- Jankju, Mohammad -- Liu, Jushan -- Mau, Rebecca L -- Miriti, Maria -- Monerris, Jorge -- Naseri, Kamal -- Noumi, Zouhaier -- Polo, Vicente -- Prina, Anibal -- Pucheta, Eduardo -- Ramirez, Elizabeth -- Ramirez-Collantes, David A -- Romao, Roberto -- Tighe, Matthew -- Torres, Duilio -- Torres-Diaz, Cristian -- Ungar, Eugene D -- Val, James -- Wamiti, Wanyoike -- Wang, Deli -- Zaady, Eli -- England -- Nature. 2013 Oct 31;502(7473):672-6. doi: 10.1038/nature12670.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Departamento de Sistemas Fisicos, Quimicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera, kilometro 1, 41013 Sevilla, Spain [2] Area de Biodiversidad y Conservacion, Departamento de Biologia y Geologia, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, Calle Tulipan Sin Numero, 28933 Mostoles, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24172979" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Silicates/analysis ; Biomass ; Carbon/analysis/metabolism ; Carbon Cycle ; Climate Change ; *Desert Climate ; *Desiccation ; *Ecosystem ; *Geography ; Models, Theoretical ; Nitrogen/analysis/metabolism ; Nitrogen Cycle ; Phosphoric Monoester Hydrolases/analysis/metabolism ; Phosphorus/analysis/metabolism ; Plants/metabolism ; Soil/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2012-01-17
    Description: Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558739/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3558739/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Maestre, Fernando T -- Quero, Jose L -- Gotelli, Nicholas J -- Escudero, Adrian -- Ochoa, Victoria -- Delgado-Baquerizo, Manuel -- Garcia-Gomez, Miguel -- Bowker, Matthew A -- Soliveres, Santiago -- Escolar, Cristina -- Garcia-Palacios, Pablo -- Berdugo, Miguel -- Valencia, Enrique -- Gozalo, Beatriz -- Gallardo, Antonio -- Aguilera, Lorgio -- Arredondo, Tulio -- Blones, Julio -- Boeken, Bertrand -- Bran, Donaldo -- Conceicao, Abel A -- Cabrera, Omar -- Chaieb, Mohamed -- Derak, McHich -- Eldridge, David J -- Espinosa, Carlos I -- Florentino, Adriana -- Gaitan, Juan -- Gatica, M Gabriel -- Ghiloufi, Wahida -- Gomez-Gonzalez, Susana -- Gutierrez, Julio R -- Hernandez, Rosa M -- Huang, Xuewen -- Huber-Sannwald, Elisabeth -- Jankju, Mohammad -- Miriti, Maria -- Monerris, Jorge -- Mau, Rebecca L -- Morici, Ernesto -- Naseri, Kamal -- Ospina, Abelardo -- Polo, Vicente -- Prina, Anibal -- Pucheta, Eduardo -- Ramirez-Collantes, David A -- Romao, Roberto -- Tighe, Matthew -- Torres-Diaz, Cristian -- Val, James -- Veiga, Jose P -- Wang, Deli -- Zaady, Eli -- 242658/European Research Council/International -- New York, N.Y. -- Science. 2012 Jan 13;335(6065):214-8. doi: 10.1126/science.1215442.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Area de Biodiversidad y Conservacion, Departamento de Biologia y Geologia, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, Calle Tulipan Sin Numero, 28933 Mostoles, Spain. fernando.maestre@urjc.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22246775" target="_blank"〉PubMed〈/a〉
    Keywords: *Biodiversity ; *Climate ; Climate Change ; Conservation of Natural Resources ; *Ecosystem ; Geography ; Geological Phenomena ; Models, Statistical ; *Plants ; Regression Analysis ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2016-09-20
    Description: The integron is a bacterial recombination system that allows acquisition, stockpiling and expression of cassettes carrying protein-coding sequences, and is responsible for the emergence and rise of multiresistance in Gram-negative bacteria. The functionality of this system depends on the insertion of promoterless cassettes in correct orientation, allowing their expression from the promoter located upstream of the cassette array. Correct orientation is ensured by strand selectivity of integron integrases for the bottom strand of cassette recombination sites ( attC ), recombined in form of folded single-stranded hairpins. Here, we investigated the basis of such strand selectivity by comparing recombination of wild-type and mutated attC sites with different lengths, sequences and structures. We show that all three unpaired structural features that distinguish the bottom and top strands contribute to strand selectivity. The localization of Extra-Helical Bases (EHBs) directly favors integrase binding to the bottom strand. The Unpaired Central Spacer (UCS) and the Variable Terminal Structure (VTS) influence strand selectivity indirectly, probably through the stabilization of the bottom strand and the resulting synapse due to the nucleotide skew between the two strands. These results underscore the importance of the single-stranded nature of the attC site that allows such tight control over integron cassette orientation.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 9
    Publication Date: 2015-07-01
    Description: There has been significant controversy over the mechanisms responsible for forming compact stellar systems like ultra-compact dwarfs (UCDs), with suggestions that UCDs are simply the high-mass extension of the globular cluster population, or alternatively, the liberated nuclei of galaxies tidally stripped by larger companions. Definitive examples of UCDs formed by either route have been difficult to find, with only a handful of persuasive examples of stripped-nucleus-type UCDs being known. In this paper, we present very deep Gemini/GMOS spectroscopic observations of the suspected stripped-nucleus UCD NGC 4546-UCD1 taken in good seeing conditions (〈0.7 arcsec). With these data we examine the spatially resolved kinematics and star formation history of this unusual object. We find no evidence of a rise in the central velocity dispersion of the UCD, suggesting that this UCD lacks a massive central black hole like those found in some other compact stellar systems, a conclusion confirmed by detailed dynamical modelling. Finally, we are able to use our extremely high signal-to-noise spectrum to detect a temporally extended star formation history for this UCD. We find that the UCD was forming stars since the earliest epochs until at least 1–2 Gyr ago. Taken together these observations confirm that NGC 4546-UCD1 is the remnant nucleus of a nucleated dwarf galaxy that was tidally destroyed by NGC 4546 within the last 1–2 Gyr.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 10
    Publication Date: 2024-03-15
    Description: Ocean acidification (OA)—caused by rising concentrations of carbon dioxide (CO2)—is thought to be a major threat to marine ecosystems and has been shown to induce behavioural alterations in fish. Here we show behavioural resilience to near-future OA in a commercially important and migratory marine finfish, the Sea bass (Dicentrarchus labrax). Sea bass were raised from eggs at 19°C in ambient or near-future OA (1000 µatm pCO2) conditions and n = 270 fish were observed 59–68 days post-hatch using automated tracking from video. Fish reared under ambient conditions, OA conditions, and fish reared in ambient conditions but tested in OA water showed statistically similar movement patterns, and reacted to their environment and interacted with each other in comparable ways. Thus our findings indicate behavioural resilience to near-future OA in juvenile sea bass. Moreover, simulated agent-based models indicate that our analysis methods are sensitive to subtle changes in fish behaviour. It is now important to determine whether the absences of any differences persist under more ecologically relevant circumstances and in contexts which have a more direct bearing on individual fitness.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Animalia; Aragonite saturation state; Behaviour; Bicarbonate ion; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chordata; Coast and continental shelf; Containers and aquaria (20-1000 L or 〈 1 m**2); Dicentrarchus labrax; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Laboratory experiment; Laboratory strains; Nekton; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; pH, standard deviation; Salinity; Salinity, standard deviation; Single species; Species, unique identification; Species, unique identification (Semantic URI); Species, unique identification (URI); Temperate; Temperature, water; Temperature, water, standard deviation; Treatment; Type
    Type: Dataset
    Format: text/tab-separated-values, 144 data points
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