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ecosystem collapse

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https://www.readbyqxmd.com/read/28330920/immanent-conditions-determine-imminent-collapses-nutrient-regimes-define-the-resilience-of-macroalgal-communities
#1
Jordi Boada, Rohan Arthur, David Alonso, Jordi F Pagès, Albert Pessarrodona, Silvia Oliva, Giulia Ceccherelli, Luigi Piazzi, Javier Romero, Teresa Alcoverro
Predicting where state-changing thresholds lie can be inherently complex in ecosystems characterized by nonlinear dynamics. Unpacking the mechanisms underlying these transitions can help considerably reduce this unpredictability. We used empirical observations, field and laboratory experiments, and mathematical models to examine how differences in nutrient regimes mediate the capacity of macrophyte communities to sustain sea urchin grazing. In relatively nutrient-rich conditions, macrophyte systems were more resilient to grazing, shifting to barrens beyond 1 800 g m(-2) (urchin biomass), more than twice the threshold of nutrient-poor conditions...
March 29, 2017: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/28293421/protein-misfolding-in-neurodegenerative-diseases-implications-and-strategies
#2
REVIEW
Patrick Sweeney, Hyunsun Park, Marc Baumann, John Dunlop, Judith Frydman, Ron Kopito, Alexander McCampbell, Gabrielle Leblanc, Anjli Venkateswaran, Antti Nurmi, Robert Hodgson
A hallmark of neurodegenerative proteinopathies is the formation of misfolded protein aggregates that cause cellular toxicity and contribute to cellular proteostatic collapse. Therapeutic options are currently being explored that target different steps in the production and processing of proteins implicated in neurodegenerative disease, including synthesis, chaperone-assisted folding and trafficking, and degradation via the proteasome and autophagy pathways. Other therapies, like mTOR inhibitors and activators of the heat shock response, can rebalance the entire proteostatic network...
2017: Translational Neurodegeneration
https://www.readbyqxmd.com/read/28275729/radar-interferometry-offers-new-insights-into-threats-to-the-angkor-site
#3
Fulong Chen, Huadong Guo, Peifeng Ma, Hui Lin, Cheng Wang, Natarajan Ishwaran, Peou Hang
The conservation of World Heritage is critical to the cultural and social sustainability of regions and nations. Risk monitoring and preventive diagnosis of threats to heritage sites in any given ecosystem are a complex and challenging task. Taking advantage of the performance of Earth Observation technologies, we measured the impacts of hitherto imperceptible and poorly understood factors of groundwater and temperature variations on the monuments in the Angkor World Heritage site (400 km(2)). We developed a two-scale synthetic aperture radar interferometry (InSAR) approach...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28261659/climate-impacts-on-global-hot-spots-of-marine-biodiversity
#4
Francisco Ramírez, Isabel Afán, Lloyd S Davis, André Chiaradia
Human activities drive environmental changes at scales that could potentially cause ecosystem collapses in the marine environment. We combined information on marine biodiversity with spatial assessments of the impacts of climate change to identify the key areas to prioritize for the conservation of global marine biodiversity. This process identified six marine regions of exceptional biodiversity based on global distributions of 1729 species of fish, 124 marine mammals, and 330 seabirds. Overall, these hot spots of marine biodiversity coincide with areas most severely affected by global warming...
February 2017: Science Advances
https://www.readbyqxmd.com/read/28221708/improved-management-of-small-pelagic-fisheries-through-seasonal-climate-prediction
#5
Désirée Tommasi, Charles A Stock, Kathleen Pegion, Gabriel A Vecchi, Richard D Methot, Michael A Alexander, David M Checkley
Populations of small pelagic fish are strongly influenced by climate. The inability of managers to anticipate environment-driven fluctuations in stock productivity or distribution can lead to overfishing and stock collapses, inflexible management regulations inducing shifts in the functional response to human predators, lost opportunities to harvest populations, bankruptcies in the fishing industry, and loss of resilience in the human food supply. Recent advances in dynamical global climate prediction systems allow for sea surface temperature (SST) anomaly predictions at a seasonal scale over many shelf ecosystems...
October 12, 2016: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/28211914/eco-evolutionary-feedbacks-can-rescue-cooperation-in-microbial-populations
#6
Clara Moreno-Fenoll, Matteo Cavaliere, Esteban Martínez-García, Juan F Poyatos
Bacterial populations whose growth depends on the cooperative production of public goods are usually threatened by the rise of cheaters that do not contribute but just consume the common resource. Minimizing cheater invasions appears then as a necessary mechanism to maintain these populations. However, that invasions result instead in the persistence of cooperation is a prospect that has yet remained largely unexplored. Here, we show that the demographic collapse induced by cheaters in the population can actually contribute to the rescue of cooperation, in a clear illustration of how ecology and evolution can influence each other...
February 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28190724/flourishing-sponge-based-ecosystems-after-the-end-ordovician-mass-extinction
#7
Joseph P Botting, Lucy A Muir, Yuandong Zhang, Xuan Ma, Junye Ma, Longwu Wang, Jianfang Zhang, Yanyan Song, Xiang Fang
The Late Ordovician (Hirnantian, approximately 445 million years ago) extinction event was among the largest known, with 85% species loss [1]. Post-extinction survival faunas are invariably low diversity, especially benthic communities [2], but ecological structure was restored relatively rapidly [1]. This pattern, however, reflects organisms with robust skeletons, as only one exceptionally preserved Hirnantian fossil biota was previously known [3, 4]; in particular, almost no Hirnantian sponges have been recorded...
February 20, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28176452/overlooking-the-smallest-matter-viruses-impact-biological-invasions
#8
REVIEW
Cara A Faillace, Nicholas S Lorusso, Siobain Duffy
Parasites and pathogens have recently received considerable attention for their ability to affect biological invasions, however, researchers have largely overlooked the distinct role of viruses afforded by their unique ability to rapidly mutate and adapt to new hosts. With high mutation and genomic substitution rates, RNA and single-stranded DNA (ssDNA) viruses may be important constituents of invaded ecosystems, and could potentially behave quite differently from other pathogens. We review evidence suggesting that rapidly evolving viruses impact invasion dynamics in three key ways: (1) Rapidly evolving viruses may prevent exotic species from establishing self-sustaining populations...
February 8, 2017: Ecology Letters
https://www.readbyqxmd.com/read/28174316/density-dependent-recycling-promotes-the-long-term-survival-of-bacterial-populations-during-periods-of-starvation
#9
Sotaro Takano, Bogna J Pawlowska, Ivana Gudelj, Tetsuya Yomo, Saburo Tsuru
The amount of natural resources in the Earth's environment is in flux, which can trigger catastrophic collapses of ecosystems. How populations survive under nutrient-poor conditions is a central question in ecology. Curiously, some bacteria persist for a long time in nutrient-poor environments. Although this survival may be accomplished through cell death and the recycling of dead cells, the importance of these processes and the mechanisms underlying the survival of the populations have not been quantitated...
February 7, 2017: MBio
https://www.readbyqxmd.com/read/28174111/hunting-cooperation-and-allee-effects-in-predators
#10
Mickaël Teixeira Alves, Frank M Hilker
Cooperation is a ubiquitous behavior in many biological systems and is well-known for promoting Allee effects. However, few studies have paid attention to mechanisms inducing Allee effects in predators. Here, we focus on hunting cooperation and use a classical predator-prey system for identifying the impact of this mechanism. We add a cooperation term to the attack rate of the predator population, and investigate the equilibrium stability in phase plane and bifurcation diagrams. We show that hunting cooperation can be beneficial to the predator population by increasing the attack rate...
February 5, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28132402/direct-and-indirect-climate-change-effects-on-carbon-dioxide-fluxes-in-a-thawing-boreal-forest-wetland-landscape
#11
Manuel Helbig, Laura E Chasmer, Ankur R Desai, Natascha Kljun, William L Quinton, Oliver Sonnentag
In the sporadic permafrost zone of northwestern Canada, boreal forest carbon dioxide (CO2 ) fluxes will be altered directly by climate change through changing meteorological forcing and indirectly through changes in landscape functioning associated with thaw-induced collapse-scar bog ("wetland") expansion. However, their combined effect on landscape-scale net ecosystem CO2 exchange (NEELAND ), resulting from changing gross primary productivity (GPP) and ecosystem respiration (ER), remains unknown. Here, we quantify indirect land cover change impacts on NEELAND and direct climate change impacts on modeled temperature- and light-limited NEELAND of a boreal forest-wetland landscape...
January 28, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28120950/fencing-bodes-a-rapid-collapse-of-the-unique-greater-mara-ecosystem
#12
Mette Løvschal, Peder Klith Bøcher, Jeppe Pilgaard, Irene Amoke, Alice Odingo, Aggrey Thuo, Jens-Christian Svenning
With land privatization and fencing of thousands of hectares of communal grazing areas, East Africa is struggling with one of the most radical cultural and environmental changes in its history. The 668,500-hectare Greater Mara is of crucial importance for the great migrations of large mammals and for Maasai pastoralist culture. However, the magnitude and pace of these fencing processes in this area are almost completely unknown. We provide new evidence that fencing is appropriating land in this area at an unprecedented and accelerating speed and scale...
January 25, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28106043/humans-rather-than-climate-the-primary-cause-of-pleistocene-megafaunal-extinction-in-australia
#13
Sander van der Kaars, Gifford H Miller, Chris S M Turney, Ellyn J Cook, Dirk Nürnberg, Joachim Schönfeld, A Peter Kershaw, Scott J Lehman
Environmental histories that span the last full glacial cycle and are representative of regional change in Australia are scarce, hampering assessment of environmental change preceding and concurrent with human dispersal on the continent ca. 47,000 years ago. Here we present a continuous 150,000-year record offshore south-western Australia and identify the timing of two critical late Pleistocene events: wide-scale ecosystem change and regional megafaunal population collapse. We establish that substantial changes in vegetation and fire regime occurred ∼70,000 years ago under a climate much drier than today...
January 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28100827/insights-into-resource-consumption-cross-feeding-system-collapse-stability-and-biodiversity-from-an-artificial-ecosystem
#14
Yu Liu, David Sumpter
Community ecosystems at very different levels of biological organization often have similar properties. Coexistence of multiple species, cross-feeding, biodiversity and fluctuating population dynamics are just a few of the properties that arise in a range of ecological settings. Here we develop a bottom-up model of consumer-resource interactions, in the form of an artificial ecosystem 'number soup', which reflects basic properties of many bacterial and other community ecologies. We demonstrate four key properties of the number soup model: (i) communities self-organize so that all available resources are fully consumed; (ii) reciprocal cross-feeding is a common evolutionary outcome, which evolves in a number of stages, and many transitional species are involved; (iii) the evolved ecosystems are often 'robust yet fragile', with keystone species required to prevent the whole system from collapsing; (iv) non-equilibrium dynamics and chaotic patterns are general properties, readily generating rich biodiversity...
January 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28052391/the-present-is-the-key-to-the-past-linking-regime-shifts-in-kelp-beds-to-the-distribution-of-deep-living-sea-urchins
#15
Karen Filbee-Dexter, Robert E Scheibling
Understanding processes that drive sudden shifts in ecosystem structure and function has become an important research focus for coastal management. In kelp bed ecosystems, regime shifts occur when high densities of sea urchins destructively graze kelp and create coralline algal barrens. While the importance of predation and disease in mediating shifts between kelp beds and barrens on shallow rocky reefs has been well documented, little is known about the role of deep-living urchins in these alternative stable-state dynamics...
January 2017: Ecology
https://www.readbyqxmd.com/read/28051127/population-cycles-and-species-diversity-in-dynamic-kill-the-winner-model-of-microbial-ecosystems
#16
Sergei Maslov, Kim Sneppen
Determinants of species diversity in microbial ecosystems remain poorly understood. Bacteriophages are believed to increase the diversity by the virtue of Kill-the-Winner infection bias preventing the fastest growing organism from taking over the community. Phage-bacterial ecosystems are traditionally described in terms of the static equilibrium state of Lotka-Volterra equations in which bacterial growth is exactly balanced by losses due to phage predation. Here we consider a more dynamic scenario in which phage infections give rise to abrupt and severe collapses of bacterial populations whenever they become sufficiently large...
January 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28039973/tangent-map-intermittency-as-an-approximate-analysis-of-intermittency-in-a-high-dimensional-fully-stochastic-dynamical-system-the-tangled-nature-model
#17
Alvaro Diaz-Ruelas, Henrik Jeldtoft Jensen, Duccio Piovani, Alberto Robledo
It is well known that low-dimensional nonlinear deterministic maps close to a tangent bifurcation exhibit intermittency and this circumstance has been exploited, e.g., by Procaccia and Schuster [Phys. Rev. A 28, 1210 (1983)], to develop a general theory of 1/f spectra. This suggests it is interesting to study the extent to which the behavior of a high-dimensional stochastic system can be described by such tangent maps. The Tangled Nature (TaNa) Model of evolutionary ecology is an ideal candidate for such a study, a significant model as it is capable of reproducing a broad range of the phenomenology of macroevolution and ecosystems...
December 2016: Chaos
https://www.readbyqxmd.com/read/28036061/honey-bee-colonies-remote-monitoring-system
#18
Sergio Gil-Lebrero, Francisco Javier Quiles-Latorre, Manuel Ortiz-López, Víctor Sánchez-Ruiz, Victoria Gámiz-López, Juan Jesús Luna-Rodríguez
Bees are very important for terrestrial ecosystems and, above all, for the subsistence of many crops, due to their ability to pollinate flowers. Currently, the honey bee populations are decreasing due to colony collapse disorder (CCD). The reasons for CCD are not fully known, and as a result, it is essential to obtain all possible information on the environmental conditions surrounding the beehives. On the other hand, it is important to carry out such information gathering as non-intrusively as possible to avoid modifying the bees' work conditions and to obtain more reliable data...
December 29, 2016: Sensors
https://www.readbyqxmd.com/read/28030596/phase-shift-dynamics-of-sea-urchin-overgrazing-on-nutrified-reefs
#19
Nina Kriegisch, Simon Reeves, Craig R Johnson, Scott D Ling
Shifts from productive kelp beds to impoverished sea urchin barrens occur globally and represent a wholesale change to the ecology of sub-tidal temperate reefs. Although the theory of shifts between alternative stable states is well advanced, there are few field studies detailing the dynamics of these kinds of transitions. In this study, sea urchin herbivory (a 'top-down' driver of ecosystems) was manipulated over 12 months to estimate (1) the sea urchin density at which kelp beds collapse to sea urchin barrens, and (2) the minimum sea urchin density required to maintain urchin barrens on experimental reefs in the urbanised Port Phillip Bay, Australia...
2016: PloS One
https://www.readbyqxmd.com/read/27966551/the-respiratory-tract-microbiome-and-lung-inflammation-a-two-way-street
#20
REVIEW
G B Huffnagle, R P Dickson, N W Lukacs
The lungs are not sterile or free from bacteria; rather, they harbor a distinct microbiome whose composition is driven by different ecological rules than for the gastrointestinal tract. During disease, there is often a shift in community composition towards Gammaproteobacteria, the bacterial class that contains many common lung-associated gram-negative "pathogens." Numerous byproducts of host inflammation are growth factors for these bacteria. The extracellular nutrient supply for bacteria in the lungs, which is severely limited during health, markedly increases due to the presence of mucus and vascular permeability...
December 14, 2016: Mucosal Immunology
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