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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
#1
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
#2
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
#3
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
#4
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
#5
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
#6
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
https://www.readbyqxmd.com/read/27892495/quorum-regulated-resistance-of-vibrio-cholerae-against-environmental-bacteriophages
#7
M Mozammel Hoque, Iftekhar Bin Naser, S M Nayeemul Bari, Jun Zhu, John J Mekalanos, Shah M Faruque
Predation by bacteriophages can significantly influence the population structure of bacterial communities. Vibrio cholerae the causative agent of cholera epidemics interacts with numerous phages in the aquatic ecosystem, and in the intestine of cholera patients. Seasonal epidemics of cholera reportedly collapse due to predation of the pathogen by phages. However, it is not clear how sufficient number of the bacteria survive to seed the environment in the subsequent epidemic season. We found that bacterial cell density-dependent gene expression termed "quorum sensing" which is regulated by signal molecules called autoinducers (AIs) can protect V...
November 28, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27861926/leaf-vein-xylem-conduit-diameter-influences-susceptibility-to-embolism-and-hydraulic-decline
#8
Christine Scoffoni, Caetano Albuquerque, Craig R Brodersen, Shatara V Townes, Grace P John, Hervé Cochard, Thomas N Buckley, Andrew J McElrone, Lawren Sack
Ecosystems worldwide are facing increasingly severe and prolonged droughts during which hydraulic failure from drought-induced embolism can lead to organ or whole plant death. Understanding the determinants of xylem failure across species is especially critical in leaves, the engines of plant growth. If the vulnerability segmentation hypothesis holds within leaves, higher order veins that are most terminal in the plant hydraulic system should be more susceptible to embolism to protect the rest of the water transport system...
November 11, 2016: New Phytologist
https://www.readbyqxmd.com/read/27861768/community-disassembly-in-ephemeral-ecosystems
#9
Brian J O'Neill
Community disassembly is the non-random process of progressive species declines and losses. This process is usually studied to determine how various forces extirpate species, such as catastrophic disturbance, species invasions, habitat fragmentation, or unnatural/anthropogenic stressors. However, in ephemeral ecosystems, community disassembly is a natural and repeatable process. While many ephemeral ecosystems are aquatic (vernal pools, playa lakes, rock pools, saline lakes, phytotelmata, etc.), some disassembly patterns are applicable to other ecosystem types, including terrestrial ecosystems...
December 2016: Ecology
https://www.readbyqxmd.com/read/27853564/bushmeat-hunting-and-extinction-risk-to-the-world-s-mammals
#10
William J Ripple, Katharine Abernethy, Matthew G Betts, Guillaume Chapron, Rodolfo Dirzo, Mauro Galetti, Taal Levi, Peter A Lindsey, David W Macdonald, Brian Machovina, Thomas M Newsome, Carlos A Peres, Arian D Wallach, Christopher Wolf, Hillary Young
Terrestrial mammals are experiencing a massive collapse in their population sizes and geographical ranges around the world, but many of the drivers, patterns and consequences of this decline remain poorly understood. Here we provide an analysis showing that bushmeat hunting for mostly food and medicinal products is driving a global crisis whereby 301 terrestrial mammal species are threatened with extinction. Nearly all of these threatened species occur in developing countries where major coexisting threats include deforestation, agricultural expansion, human encroachment and competition with livestock...
October 2016: Royal Society Open Science
https://www.readbyqxmd.com/read/27828993/predators-prey-and-habitat-structure-can-key-conservation-areas-and-early-signs-of-population-collapse-be-detected-in-neotropical-forests
#11
Benoit de Thoisy, Ibrahim Fayad, Luc Clément, Sébastien Barrioz, Eddy Poirier, Valéry Gond
Tropical forests with a low human population and absence of large-scale deforestation provide unique opportunities to study successful conservation strategies, which should be based on adequate monitoring tools. This study explored the conservation status of a large predator, the jaguar, considered an indicator of the maintenance of how well ecological processes are maintained. We implemented an original integrative approach, exploring successive ecosystem status proxies, from habitats and responses to threats of predators and their prey, to canopy structure and forest biomass...
2016: PloS One
https://www.readbyqxmd.com/read/27815533/early-warning-signals-of-regime-shifts-in-coupled-human-environment-systems
#12
Chris T Bauch, Ram Sigdel, Joe Pharaon, Madhur Anand
In complex systems, a critical transition is a shift in a system's dynamical regime from its current state to a strongly contrasting state as external conditions move beyond a tipping point. These transitions are often preceded by characteristic early warning signals such as increased system variability. However, early warning signals in complex, coupled human-environment systems (HESs) remain little studied. Here, we compare critical transitions and their early warning signals in a coupled HES model to an equivalent environment model uncoupled from the human system...
December 20, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27757544/marine-ecosystem-resilience-during-extreme-deoxygenation-the-early-jurassic-oceanic-anoxic-event
#13
Bryony A Caswell, Christopher L J Frid
Global warming during the Early Jurassic, and associated widespread ocean deoxygenation, was comparable in scale with the changes projected for the next century. This study quantifies the impact of severe global environmental change on the biological traits of marine communities that define the ecological roles and functions they deliver. We document centennial-millennial variability in the biological trait composition of Early Jurassic (Toarcian) seafloor communities and examine how this changed during the event using biological traits analysis...
October 18, 2016: Oecologia
https://www.readbyqxmd.com/read/27757421/empty-forest-or-empty-rivers-a-century-of-commercial-hunting-in-amazonia
#14
André P Antunes, Rachel M Fewster, Eduardo M Venticinque, Carlos A Peres, Taal Levi, Fabio Rohe, Glenn H Shepard
The Amazon basin is the largest and most species-rich tropical forest and river system in the world, playing a pivotal role in global climate regulation and harboring hundreds of traditional and indigenous cultures. It is a matter of intense debate whether the ecosystem is threatened by hunting practices, whereby an "empty forest" loses critical ecological functions. Strikingly, no previous study has examined Amazonian ecosystem resilience through the perspective of the massive 20th century international trade in furs and skins...
October 2016: Science Advances
https://www.readbyqxmd.com/read/27703075/collapse-of-insect-gut-symbiosis-under-simulated-climate-change
#15
Yoshitomo Kikuchi, Akiyo Tada, Dmitry L Musolin, Nobuhiro Hari, Takahiro Hosokawa, Kenji Fujisaki, Takema Fukatsu
: Global warming impacts diverse organisms not only directly but also indirectly via other organisms with which they interact. Recently, the possibility that elevated temperatures resulting from global warming may substantially affect biodiversity through disrupting mutualistic/parasitic associations has been highlighted. Here we report an experimental demonstration that global warming can affect a pest insect via suppression of its obligate bacterial symbiont. The southern green stinkbug Nezara viridula depends on a specific gut bacterium for its normal growth and survival...
October 4, 2016: MBio
https://www.readbyqxmd.com/read/27696581/predator-prey-interactions-among-permo-triassic-terrestrial-vertebrates-as-a-deterministic-factor-influencing-faunal-collapse-and-turnover
#16
Jacqueline Codron, Jennifer Botha-Brink, Daryl Codron, Adam K Huttenlocker, Kenneth D Angielczyk
Unlike modern mammalian communities, terrestrial Paleozoic and Mesozoic vertebrate systems were characterized by carnivore faunas that were as diverse as their herbivore faunas. The comparatively narrow food base available to carnivores in these paleosystems raises the possibility that predator-prey interactions contributed to unstable ecosystems by driving populations to extinction. Here we develop a model of predator-prey interactions based on diversity, abundance, and body size patterns observed in the Permo-Triassic vertebrate fossil record of the Karoo Basin, South Africa...
October 1, 2016: Journal of Evolutionary Biology
https://www.readbyqxmd.com/read/27660203/delayed-threshold-response-of-a-rodent-population-to-human-induced-landscape-change
#17
Andrey V Tchabovsky, Ludmila E Savinetskaya, Elena N Surkova, Natalia L Ovchinnikova, Ivan A Kshnyasev
Theory predicts that due to their resilience, ecosystems and populations are expected to respond to environmental changes not gradually, but in a nonlinear way with sudden abrupt shifts. However, it is not easy to observe and predict the state-and-transition dynamics in the real world because of time lags between exogenous perturbations and species response. Based on yearly surveys, during 21 years (1994-2014), we have studied population dynamics of a desert rodent (the midday gerbil, Meriones meridianus) in the rangelands of southern Russia under landscape change from desert to steppe caused by the drastic reduction of livestock after the collapse of the USSR in the early 1990s...
December 2016: Oecologia
https://www.readbyqxmd.com/read/27648228/early-warning-signals-detect-critical-impacts-of-experimental-warming
#18
Lauren Jarvis, Kevin McCann, Tyler Tunney, Gabriel Gellner, John M Fryxell
Earth's surface temperatures are projected to increase by ~1-4°C over the next century, threatening the future of global biodiversity and ecosystem stability. While this has fueled major progress in the field of physiological trait responses to warming, it is currently unclear whether routine population monitoring data can be used to predict temperature-induced population collapse. Here, we integrate trait performance theory with that of critical tipping points to test whether early warning signals can be reliably used to anticipate thermally induced extinction events...
September 2016: Ecology and Evolution
https://www.readbyqxmd.com/read/27643946/architecture-of-collapse-regime-shift-and-recovery-in-an-hierarchically-structured-marine-ecosystem
#19
Georgi M Daskalov, Laura Boicenco, Alexandre N Grishin, Luminita Lazar, Vesselina Mihneva, Vladislav A Shlyakhov, Mustafa Zengin
By the late 20th century, a series of events or 'natural experiments', for example the depletion of apex predators, extreme eutrophication and blooms of invasive species, had suggested that the Black Sea could be considered as a large ecosystem 'laboratory'. The events resulted in regime shifts cascading through all trophic levels, disturbing ecosystem functioning and damaging the water environment. Causal pathways by which the external (hydroclimate, overfishing) and internal (food web interactions) drivers provoke regime shifts are investigated...
September 19, 2016: Global Change Biology
https://www.readbyqxmd.com/read/27629038/spatially-cascading-effect-of-perturbations-in-experimental-meta-ecosystems
#20
Eric Harvey, Isabelle Gounand, Pravin Ganesanandamoorthy, Florian Altermatt
Ecosystems are linked to neighbouring ecosystems not only by dispersal, but also by the movement of subsidy. Such subsidy couplings between ecosystems have important landscape-scale implications because perturbations in one ecosystem may affect community structure and functioning in neighbouring ecosystems via increased/decreased subsidies. Here, we combine a general theoretical approach based on harvesting theory and a two-patch protist meta-ecosystem experiment to test the effect of regional perturbations on local community dynamics...
September 14, 2016: Proceedings. Biological Sciences
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